all_posts_clean.txt

Id|Title|Body
3061|"Calling a function of a module from a string with the function's name"|"What is the best way to go about calling a function given a string with the function's name in a Python program.  For example, let's say that I have a module <code>foo</code>, and I have a string whose contents are <code>""bar""</code>. What is the best way to go about calling <code>foo.bar()</code>?

I need to get the return value of the function, which is why I don't just use <code>eval</code>. I figured out how to do it by using <code>eval</code> to define a temp function that returns the result of that function call, but I'm hoping that there is a more elegant way to do this.
"
19151|"Build a Basic Python Iterator"|"How would one create an iterative function (or iterator object) in python?
"
22617|"Format numbers to strings in Python"|"I need to find out how to format numbers as strings. My code is here:

<code>return str(hours)+"":""+str(minutes)+"":""+str(seconds)+"" ""+ampm
</code>

Hours and minutes are integers, and seconds is a float.  the str() function will convert all of these numbers to the tenths (0.1) place.  So instead of my string outputting ""5:30:59.07 pm"", it would display something like ""5.0:30.0:59.1 pm"".

Bottom line, what library / function do I need to do this for me?
"
22676|"How do I download a file over HTTP using Python?"|"I have a small utility that I use to download a MP3 from a website on a schedule and then builds/updates a podcast XML file which I've obviously added to iTunes.

The text processing that creates/updates the XML file is written in Python. I use wget inside a Windows <code>.bat</code> file to download the actual MP3 however. I would prefer to have the entire utility written in Python though.

I struggled though to find a way to actually down load the file in Python, thus why I resorted to <code>wget</code>.

So, how do I download the file using Python?
"
25665|"Python module for converting PDF to text"|"Which are the best Python modules to convert PDF files into text? 
"
35988|"C-like structures in Python"|"Is there a way to conveniently define a C-like structure in Python? I'm tired of writing stuff like:

<code>class MyStruct():
    def __init__(self, field1, field2, field3):
        self.field1 = field1
        self.field2 = field2
        self.field3 = field3
</code>
"
36139|"How to sort a list of strings?"|"What is the best way of creating an alphabetically sorted list in Python?
"
36901|"What does ** (double star) and * (star) do for parameters?"|"In the following method definitions, what does the <code>*</code> and <code>**</code> do for <code>param2</code>?

<code>def foo(param1, *param2):
def bar(param1, **param2):
</code>
"
36932|"How can I represent an 'Enum' in Python?"|"I'm mainly a C# developer, but I'm currently working on a project in Python.

How can I represent the equivalent of an Enum in Python?  
"
38987|"How to merge two dictionaries in a single expression?"|"I have two Python dictionaries, and I want to write a single expression that returns these two dictionaries, merged.  The <code>update()</code> method would be what I need, if it returned its result instead of modifying a dict in-place.

<code>&gt;&gt;&gt; x = {'a':1, 'b': 2}
&gt;&gt;&gt; y = {'b':10, 'c': 11}
&gt;&gt;&gt; z = x.update(y)
&gt;&gt;&gt; print(z)
None
&gt;&gt;&gt; x
{'a': 1, 'b': 10, 'c': 11}
</code>

How can I get that final merged dict in <code>z</code>, not <code>x</code>?

(To be extra-clear, the last-one-wins conflict-handling of <code>dict.update()</code> is what I'm looking for as well.)
"
39086|"Search and replace a line in a file in Python"|"I want to loop over the contents of a text file and do a search and replace on some lines and write the result back to the file. I could first load the whole file in memory and then write it back, but that probably is not the best way to do it.

What is the best way to do this, within the following code?

<code>f = open(file)
for line in f:
    if line.contains('foo'):
        newline = line.replace('foo', 'bar')
        # how to write this newline back to the file
</code>
"
44778|"How would you make a comma-separated string from a list?"|"What would be your preferred way to concatenate strings from a sequence such that between each two consecutive pair a comma is added. That is, how do you map, for instance, <code>[ 'a', 'b', 'c' ]</code> to <code>'a,b,c'</code>? (The cases <code>[ s ]</code> and <code>[]</code> should be mapped to <code>s</code> and <code>''</code>, respectively.)

I usually end up using something like <code>''.join(map(lambda x: x+',',l))[:-1]</code>, but also feeling somewhat unsatisfied.

Edit: I'm both ashamed and happy that the solution is so simple. Obviously I have hardly a clue as to what I'm doing. (I probably needed ""simple"" concatenation in the past and somehow memorised <code>s.join([e1,e2,...])</code> as a shorthand for <code>s+e1+e2+...</code>.)
"
50499|"How do I get the path and name of the file that is currently executing?"|"I have scripts calling other script files but I need to get the filepath of the file that is currently running within the process. 

For example, let's say I have three files. Using execfile:


<code>script_1.py</code> calls <code>script_2.py</code>. 
In turn, <code>script_2.py</code> calls <code>script_3.py</code>. 


How can I get the file name and path of <code>script_3.py</code>, from code within <code>script_3.py</code>, without having to pass that information as arguments from <code>script_2.py</code>?

(Executing <code>os.getcwd()</code> returns the original starting script's filepath not the current file's.)
"
51520|"How to get an absolute file path in Python"|"Given a path such as <code>""mydir/myfile.txt""</code>, how do I find the absolute filepath relative to the current working directory in Python? E.g. on Windows, I might end up with:

<code>""C:/example/cwd/mydir/myfile.txt""
</code>
"
53162|"How can I do a line break (line continuation) in Python?"|"I have a long line of code that I want to break up among multiple lines. What do I use and what is the syntax?

For example, adding a bunch of strings,

<code>e = 'a' + 'b' + 'c' + 'd'
</code>

and have it like this:

<code>e = 'a' + 'b' +
    'c' + 'd'
</code>
"
53513|"Best way to check if a list,tuple or dict is empty"|"For example, if passed the following:
<code>a = []</code>  or <code>a={}</code> or <code>a=()</code>
How do I check to see if <code>a</code> is empty?
"
56011|"Single quotes vs. double quotes in Python"|"According to the documentation, they're pretty much interchangeable.  Is there a stylistic reason to use one over the other?
"
60208|"Replacements for switch statement in Python?"|"I want to write a function in Python that returns different fixed values based on the value of an input index.  

In other languages I would use a <code>switch</code> or <code>case</code> statement, but Python does not appear to have a <code>switch</code> statement.  What are the recommended Python solutions in this scenario?
"
67631|"How to import a module given the full path?"|"How can I load a Python module given its full path? Note that the file can be anywhere in the filesystem, as it is a configuration option.
"
68645|"Static class variables in Python"|"Is it possible to have static class variables or methods in python? What syntax is required to do this?
"
70528|"Why are Python's 'private' methods not actually private?"|"Python gives us the ability to create 'private' methods and variables within a class by prepending double underscores to the name, like this: <code>__myPrivateMethod()</code>. How, then, can one explain this

<code>>>> class MyClass:
...     def myPublicMethod(self):
...             print 'public method'
...     def __myPrivateMethod(self):
...             print 'this is private!!'
... 
>>> obj = MyClass()
>>> obj.myPublicMethod()
public method
>>> obj.__myPrivateMethod()
Traceback (most recent call last):
  File """", line 1, in 
AttributeError: MyClass instance has no attribute '__myPrivateMethod'
>>> dir(obj)
['_MyClass__myPrivateMethod', '__doc__', '__module__', 'myPublicMethod']
>>> obj._MyClass__myPrivateMethod()
this is private!!
</code>

What's the deal?!

I'll explain this a little for those who didn't quite get that.

<code>>>> class MyClass:
...     def myPublicMethod(self):
...             print 'public method'
...     def __myPrivateMethod(self):
...             print 'this is private!!'
... 
>>> obj = MyClass()
</code>

What I did there is create a class with a public method and a private method and instantiate it.

Next, I call its public method.

<code>>>> obj.myPublicMethod()
public method
</code>

Next, I try and call its private method.

<code>>>> obj.__myPrivateMethod()
Traceback (most recent call last):
  File """", line 1, in 
AttributeError: MyClass instance has no attribute '__myPrivateMethod'
</code>

Everything looks good here; we're unable to call it. It is, in fact, 'private'. Well, actually it isn't. Running dir() on the object reveals a new magical method that python creates magically for all of your 'private' methods.

<code>>>> dir(obj)
['_MyClass__myPrivateMethod', '__doc__', '__module__', 'myPublicMethod']
</code>

This new method's name is always an underscore, followed by the class name, followed by the method name.

<code>>>> obj._MyClass__myPrivateMethod()
this is private!!
</code>

So much for encapsulation, eh?

In any case, I'd always heard Python doesn't support encapsulation, so why even try? What gives?
"
70797|"Python: user input and commandline arguments"|"How do I have a Python script that can accept user input (assuming this is possible) and how do I make it read in arguments if run from the command line?
"
72852|"How to do relative imports in Python?"|"Imagine this directory structure:

<code>app/
   __init__.py
   sub1/
      __init__.py
      mod1.py
   sub2/
      __init__.py
      mod2.py
</code>

I'm coding <code>mod1</code>, and I need to import something from <code>mod2</code>. How should I do it?  

I tried <code>from ..sub2 import mod2</code> but I'm getting an ""Attempted relative import in non-package"".

I googled around but found only ""<code>sys.path</code> manipulation"" hacks. Isn't there a clean way?  



Edit: all my <code>__init__.py</code>'s are currently empty  

Edit2: I'm trying to do this because sub2 contains classes that are shared across sub packages (<code>sub1</code>, <code>subX</code>, etc.).

Edit3: The behaviour I'm looking for is the same as described in PEP 366 (thanks John B)
"
72899|"How do I sort a list of dictionaries by values of the dictionary in Python?"|"I got a list of dictionaries and want that to be sorted by a value of that dictionary.

This

<code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code>

sorted by name, should become

<code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code>
"
73663|"Terminating a Python script"|"I am aware of the <code>die()</code> command in PHP which stops a script early.

How can I do this in Python?
"
79797|"How do I convert local time to UTC in Python?"|"How do I convert a datetime string in local time to a string in UTC time?

I'm sure I've done this before, but can't find it and SO will hopefully help me (and others) do that in future.

Clarification:  For example, if I have <code>2008-09-17 14:02:00</code> in my local timezone (<code>+10</code>), I'd like to generate a string with the equivalent <code>UTC</code> time: <code>2008-09-17 04:02:00</code>.

Also, from http://lucumr.pocoo.org/2011/7/15/eppur-si-muove/, note that in general this isn't possible as with DST and other issues there is no unique conversion from local time to UTC time.
"
82831|"How do I check whether a file exists using Python?"|"How do I check whether a file exists, without using the <code>try</code> statement?
"
85451|"Python - time.clock() vs. time.time() - accuracy?"|"Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?

for example:

<code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code>

vs.

<code>start = time.time()
... do something
elapsed = (time.time() - start)
</code>
"
89228|"Calling an external command in Python"|"How can I call an external command (as if I'd typed it at the Unix shell or Windows command prompt) from within a Python script?
"
94935|"What is the difference between range and xrange functions in Python 2.X?"|"Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about

<code>for i in range(0, 20):
for i in xrange(0, 20):
</code>
"
100003|"What is a metaclass in Python?"|"What are metaclasses? What do you use them for?
"
101268|"Hidden features of Python"|"What are the lesser-known but useful features of the Python programming language?


Try to limit answers to Python core.
One feature per answer.
Give an example and short description of the feature, not just a link to documentation.
Label the feature using a title as the first line.


Quick links to answers:


Argument Unpacking
Braces
Chaining Comparison Operators
Decorators
Default Argument Gotchas / Dangers of Mutable Default arguments
Descriptors
Dictionary default <code>.get</code> value
Docstring Tests
Ellipsis Slicing Syntax
Enumeration
For/else
Function as iter() argument
Generator expressions
<code>import this</code>
In Place Value Swapping
List stepping
<code>__missing__</code> items
Multi-line Regex
Named string formatting
Nested list/generator comprehensions
New types at runtime
<code>.pth</code> files
ROT13 Encoding
Regex Debugging
Sending to Generators
Tab Completion in Interactive Interpreter
Ternary Expression
<code>try/except/else</code>
Unpacking+<code>print()</code> function
<code>with</code> statement

"
101754|"Is there a way to run Python on Android?"|"We are working on an S60 version and this platform has a nice Python API. 

However, there is nothing official about Python on Android, but since Jython exists, is there a way to let the snake and the robot work together?
"
104420|"How to generate all permutations of a list in Python"|"How do you generate all the permutations of a list in Python, independently of the type of elements in that list?

For example:

<code>permutations([])
[]

permutations([1])
[1]

permutations([1, 2])
[1, 2]
[2, 1]

permutations([1, 2, 3])
[1, 2, 3]
[1, 3, 2]
[2, 1, 3]
[2, 3, 1]
[3, 1, 2]
[3, 2, 1]
</code>

EDIT:
Eliben pointed to a solution that's similar to mine although simpler, so I'm choosing it as the accepted answer, although Python 2.6+ has a builtin solution in the itertools module:

<code>import itertools
itertools.permutations([1, 2, 3])
</code>
"
120656|"Directory listing in Python"|"How do I get a list of all files (and directories) in a given directory in Python?
"
122327|"How do I find the location of my Python site-packages directory?"|"How do I find the location of my site-packages directory?
"
123198|"How do I copy a file in python?"|"How do I copy a file in Python? I couldn't find anything under <code>os</code>.
"
125703|"How to modify a text file?"|"I'm using Python, and would like to insert a string into a text file without deleting or copying the file. How can I do that?
"
126524|"Iterate a list with indexes in Python"|"I could swear I've seen the function (or method) that takes a list, like this <code>[3, 7, 19]</code> and makes it into iterable list of tuples, like so: <code>[(0,3), (1,7), (2,19)]</code> to use it instead of:

<code>for i in range(len(name_of_list)):
    name_of_list[i] = something
</code>

but I can't remember the name and googling ""iterate list"" gets nothing.
"
127803|"How to parse an ISO 8601-formatted date?"|"I need to parse RFC 3339 strings like <code>""2008-09-03T20:56:35.450686Z""</code> into Python's <code>datetime</code> type.

I have found <code>strptime</code> in the Python standard library, but it is not very convenient.

What is the best way to do this?
"
134934|"Display number with leading zeros"|"Given:

<code>a = 1
b = 10
c = 100
</code>

I want to display a leading zero for all numbers with less than 2 digits, i.e.:

<code>01
10
100
</code>
"
136097|"What is the difference between @staticmethod and @classmethod in Python?"|"What is the difference between a function decorated with <code>@staticmethod</code> and one decorated with <code>@classmethod</code>?
"
139180|"listing all functions in a python module"|"I have a python module installed on my system and I'd like to be able to see what functions/classes/methods are available in it.   

I want to call the doc function on each one. In ruby I can do something like ClassName.methods to get a list of all the methods available on that class. Is there something similar in python?

eg. something like:

<code>from somemodule import foo
print foo.methods # or whatever is the correct method to call
</code>
"
145270|"Calling C/C++ from python?"|"What would be the quickest way to construct a python binding to a C or C++ library?

(using windows if this matters)
"
151199|"How do I calculate number of days betwen two dates using Python?"|"If I have two dates (ex. <code>'8/18/2008'</code> and <code>'9/26/2008'</code>) what is the best way to get the difference measured in days?
"
152580|"What's the canonical way to check for type in python?"|"What is the best way to check whether a given object is of a given type? How about checking whether the object inherits from a given type?

Let's say I have an object <code>o</code>. How do I check whether it's a <code>str</code>?
"
159720|"What is the naming convention in Python for variable and function names?"|"Coming from a C# background the naming convention for variables and method names are usually either CamelCase or Pascal Case:

<code>// C# example
string thisIsMyVariable = ""a""
public void ThisIsMyMethod()
</code>

In Python, I have seen the above but I have also seen underscores being used:

<code># python example
this_is_my_variable = 'a'
def this_is_my_function():
</code>

Is there a more preferable, definitive coding style for Python?
"
166506|"Finding local IP addresses using Python's stdlib"|"How can I find local IP addresses (i.e. 192.168.x.x or 10.0.x.x) in Python platform independently and using only the standard library?
"
172439|"How do I split a multi-line string into multiple lines?"|"I have a multi-line string literal that I want to do an operation on each line, like so:

<code>inputString = """"""Line 1
Line 2
Line 3""""""
</code>

I want to do something like the following:

<code>for line in inputString:
    doStuff()
</code>
"
176011|"Python List vs. Array - when to use?"|"If you are creating a 1d array, you can implement it as a List, or else use the 'array' module in the standard library.  I have always used Lists for 1d arrays.

What is the reason or circumstance where I would want to use the array module instead?

Is it for performance and memory optimization, or am I missing something obvious?
"
176918|"Finding the index of an item given a list containing it in Python"|"For a list <code>[""foo"", ""bar"", ""baz""]</code> and an item in the list <code>""bar""</code>, what's the cleanest way to get its index (1) in Python?
"
179369|"How do I abort the execution of a Python script?"|"
  Possible Duplicate:
  Terminating a Python script  




I have a simple Python script that I want to stop executing if a condition is met.

For example:

<code>done = True
if done:
    # quit/stop/exit
else:
    # do other stuff
</code>

Essentially, I am looking for something that behaves equivalently to the 'return' keyword in the body of a function which allows the flow of the code to exit the function and not execute the remaining code.
"
181530|"Styling multi-line conditions in 'if' statements?"|"Sometimes I break long conditions in <code>if</code>s onto several lines. The most obvious way to do this is:

<code>  if (cond1 == 'val1' and cond2 == 'val2' and
      cond3 == 'val3' and cond4 == 'val4'):
      do_something
</code>

Isn't very very appealing visually, because the action blends with the conditions. However, it is the natural way using correct Python indentation of 4 spaces.

For the moment I'm using:

<code>  if (    cond1 == 'val1' and cond2 == 'val2' and
          cond3 == 'val3' and cond4 == 'val4'):
      do_something
</code>

But this isn't very pretty. :-)

Can you recommend an alternative way?
"
183853|"In Python 2, what is the difference between '/' and '//' when used for division?"|"Is there a benefit to using one over the other? In Python 2, they both seem to return the same results:

<code>&gt;&gt;&gt; 6/3
2
&gt;&gt;&gt; 6//3
2
</code>
"
185936|"Delete Folder Contents in Python"|"How can I delete the contents of a local folder in Python?

The current project is for Windows but I would like to see *nix also.
"
191010|"How to get a complete list of object's methods and attributes?"|"<code>dir(re.compile(pattern)) 
</code>

does not return pattern as one of the lists's elements. Namely it returns:

<code>['__copy__', '__deepcopy__', 'findall', 'finditer', 'match', 'scanner', 'search', 'split', 'sub', 'subn']
</code>

According to the manual, it is supposed to contain 


  the object's attributes' names, the
  names of its class's attributes, and
  recursively of the attributes of its
  class's base classes.


It says also that


  The list is not necessarily complete.


Is there a way to get the complete list? I always assumed that dir returns a complete list but apparently it does not...

Also: is there a way to list only attributes? Or only methods?

Edit: this is actually a bug in python -> supposedly it is fixed in the 3.0 branch (and perhaps also in 2.6)
"
192109|"Is there a built-in function to print all the current properties and values of an object?"|"So what I'm looking for here is something like PHP's print_r function. This is so I can debug my scripts by seeing what's the state of the object in question.
"
204017|"How do I execute a program from python? os.system fails due to spaces in path"|"I have a python script that needs to execute an external program, but for some reason fails.

If I have the following script:

<code>import os;
os.system(""C:\\Temp\\a b c\\Notepad.exe"");
raw_input();
</code>

Then it fails with the following error:

<code>'C:\Temp\a' is not recognized as an internal or external command, operable program or batch file.
</code>

If I escape the program with quotes:

<code>import os;
os.system('""C:\\Temp\\a b c\\Notepad.exe""');
raw_input();
</code>

Then it works. However, if I add a parameter, it stops working again:

<code>import os;
os.system('""C:\\Temp\\a b c\\Notepad.exe"" ""C:\\test.txt""');
raw_input();
</code>

What is the right way to execute a program and wait for it to complete? I do not need to read output from it, as it is a visual program that does a job and then just exits, but I need to wait for it to complete.

Also note, moving the program to a non-spaced path is not an option either.



Edit This does not work either:

<code>import os;
os.system(""'C:\\Temp\\a b c\\Notepad.exe'"");
raw_input();
</code>

Note the swapped single/double quotes.

with or without a parameter to notepad here, it fails with the error message

<code>The filename, directory name, or volume label syntax is incorrect.
</code>
"
209513|"Convert hex string to int in Python"|"How do I convert a hex string to an int in Python? 

I may have it as ""<code>0xffff</code>"" or just ""<code>ffff</code>"".
"
209840|"Map two lists into a dictionary in Python"|"Imagine that you have:

<code>keys = ('name', 'age', 'food')
values = ('Monty', 42, 'spam')
</code>

What is the simplest way to produce the following dictionary ?

<code>a_dict = {'name' : 'Monty', 'age' : 42, 'food' : 'spam'}
</code>

This code works, but I'm not really proud of it :

<code>a_dict = {}
junk = map(lambda k, v: a_dict.update({k: v}), keys, values)
</code>
"
227459|"ASCII value of a character in Python"|"How do I get the ASCII value of a character as an int in Python?
"
230751|"How to flush output of Python print?"|"How do I force Python's print function to output to the screen?

This is not a duplicate of Disable output buffering - the linked question is attempting unbuffered output, while this is more general. The top answers in that question are too powerful or involved for this one (they're not good answers for this), and this question can be found on Google by a relative newbie.
"
231767|"What does the ""yield"" keyword do?"|"What is the use of the <code>yield</code> keyword in Python? What does it do?

For example, I'm trying to understand this code1:

<code>def _get_child_candidates(self, distance, min_dist, max_dist):
    if self._leftchild and distance - max_dist &lt; self._median:
        yield self._leftchild
    if self._rightchild and distance + max_dist &gt;= self._median:
        yield self._rightchild  
</code>

And this is the caller:

<code>result, candidates = list(), [self]
while candidates:
    node = candidates.pop()
    distance = node._get_dist(obj)
    if distance &lt;= max_dist and distance &gt;= min_dist:
        result.extend(node._values)
    candidates.extend(node._get_child_candidates(distance, min_dist, max_dist))
return result
</code>

What happens when the method <code>_get_child_candidates</code> is called?
Is a list returned? A single element? Is it called again? When will subsequent calls stop?




1. The code comes from Jochen Schulz (jrschulz), who made a great Python library for metric spaces. This is the link to the complete source: Module mspace.
"
237079|"How to get file creation & modification date/times in Python?"|"I have a script that needs to do some stuff based on file creation &amp; modification dates but has to run on Linux &amp; Windows.

What's the best cross-platform way to get file creation &amp; modification date/times in Python?
"
247770|"Retrieving python module path"|"I want to detect whether module has changed. Now, using inotify is simple, you just need to know the directory you want to get notifications from.

How do I retrieve a module's path in python?
"
251464|"How to get a function name as a string in Python?"|"In Python, how do I get a function name as a string without calling the function?

<code>def my_function():
    pass

print get_function_name_as_string(my_function) # my_function is not in quotes
</code>

should output <code>""my_function""</code>.

Is this available in python? If not, any idea how to write <code>get_function_name_as_string</code> in Python?
"
252703|"append vs. extend"|"What's the difference between the list methods <code>append()</code> and <code>extend()</code>?
"
265960|"Best way to strip punctuation from a string in Python"|"It seems like there should be a simpler way than:

<code>import string
s = ""string. With. Punctuation?"" # Sample string 
out = s.translate(string.maketrans("""",""""), string.punctuation)
</code>

Is there?
"
268272|"Getting key with maximum value in dictionary?"|"I have a <code>dictionary</code>: keys are strings, values are integers.

Example: 

<code>stats = {'a':1000, 'b':3000, 'c': 100}
</code>

I'd like to get <code>'b'</code> as an answer, since it's the key with a higher value.

I did the following, using an intermediate list with reversed key-value tuples:

<code>inverse = [(value, key) for key, value in stats.items()]
print max(inverse)[1]
</code>

Is that one the better (or even more elegant) approach?
"
269795|"How do I find the location of Python module sources?"|"How do I learn where the source file for a given Python module is installed? Is the method different on Windows than on Linux?

I'm trying to look for the source of the <code>datetime</code> module in particular, but I'm interested in a more general answer as well.
"
273192|"How can I create a directory if it does not exist?"|"What is the most elegant way to check if the directory a file is going to be written to exists, and if not, create the directory using Python? Here is what I tried:

<code>import os

file_path = ""/my/directory/filename.txt""
directory = os.path.dirname(file_path)

try:
    os.stat(directory)
except:
    os.mkdir(directory)       

f = file(filename)
</code>

Somehow, I missed <code>os.path.exists</code> (thanks kanja, Blair, and Douglas). This is what I have now:

<code>def ensure_dir(file_path):
    directory = os.path.dirname(file_path)
    if not os.path.exists(directory):
        os.makedirs(directory)
</code>

Is there a flag for ""open"", that makes this happen automatically?
"
273946|"How do I resize an image using PIL and maintain its aspect ratio?"|"Is there an obvious way to do this that I'm missing?  I'm just trying to make thumbnails.
"
275018|"How can I remove (chomp) a newline in Python?"|"What is the Python equivalent of Perl's <code>chomp</code> function, which removes the last character of a value?
"
279237|"Import a module from a relative path"|"How do I import a python module given its relative path?

For example, if <code>dirFoo</code> contains <code>Foo.py</code> and <code>dirBar</code>, and <code>dirBar</code> contains <code>Bar.py</code>, how do I import <code>Bar.py</code> into <code>Foo.py</code>?

Here's a visual representation:

<code>dirFoo\
    Foo.py
    dirBar\
        Bar.py
</code>

<code>Foo</code> wishes to include <code>Bar</code>, but restructuring the folder hierarchy is not an option.
"
279561|"What is the Python equivalent of static variables inside a function?"|"What is the idiomatic Python equivalent of this C/C++ code?

<code>void foo()
{
    static int counter = 0;
    counter++;
    printf(""counter is %d\n"", counter);
}
</code>

specifically, how does one implement the static member at the function level, as opposed to the class level? And does placing the function into a class change anything?
"
280243|"Python Linked List"|"What's the easiest way to use a linked list in python? In scheme, a linked list is defined simply by <code>'(1 2 3 4 5)</code>. Python's lists, <code>[1, 2, 3, 4, 5]</code>, and tuples, <code>(1, 2, 3, 4, 5)</code>, are not, in fact, linked lists, and linked lists have some nice properties such as constant-time concatenation, and being able to reference separate parts of them. Make them immutable and they are really easy to work with!
"
285289|"Exit codes in Python"|"I got a message saying <code>script xyz.py returned exit code 0</code>. What does this mean?

What do the exit codes in Python mean? How many are there? Which ones are important?
"
287871|"Print in terminal with colors using Python?"|"How can I output colored text to the terminal, in Python?
What is the best Unicode symbol to represent a solid block?
"
303200|"How do I remove/delete a folder that is not empty with Python?"|"I am getting an 'access is denied' error when I attempt to delete a folder that is not empty. I used the following command in my attempt: <code>os.remove(""/folder_name"")</code>. 

What is the most effective way of removing/deleting a folder/directory that is not empty?
"
306400|"How to randomly select an item from a list?"|"Assume I have the following list:

<code>foo = ['a', 'b', 'c', 'd', 'e']
</code>

What is the simplest way to retrieve an item at random from this list?
"
307305|"Play a Sound with Python"|"What's the easiest way to play a sound file (.wav) in Python? By easiest I mean both most platform independent and requiring the least dependencies. pygame is certainly an option, but it seems overkill for just sound.
"
311627|"How to print date in a regular format in Python?"|"This is my code:

<code>import datetime
today = datetime.date.today()
print today
</code>

This prints: 2008-11-22 which is exactly what I want BUT....I have a list I'm appending this to and then suddenly everything goes ""wonky"". Here is the code:

<code>import datetime
mylist = []
today = datetime.date.today()
mylist.append(today)
print mylist
</code>

This prints the following: 

<code>[datetime.date(2008, 11, 22)]
</code>

How on earth can I get just a simple date like ""2008-11-22""?
"
312443|"How do you split a list into evenly sized chunks?"|"I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.

I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.

I was looking for something useful in <code>itertools</code> but I couldn't find anything obviously useful. Might've missed it, though.

Related question: What is the most “pythonic” way to iterate over a list in chunks?
"
319426|"How do I do a case insensitive string comparison in Python?"|"What's the best way to do case insensitive string comparison in Python?

I would like to encapsulate comparison of a regular strings to a repository string using in a very simple and pythonic way.  I also would like to have ability to look up values in a dict hashed by strings using regular python strings.  Much obliged for advice.
"
323972|"Is there any way to kill a Thread in Python?"|"Is it possible to terminate a running thread without setting/checking any flags/semaphores/etc.?
"
328356|"Extracting text from HTML file using Python"|"I'd like to extract the text from an HTML file using Python.  I want essentially the same output I would get if I copied the text from a browser and pasted it into notepad.  

I'd like something more robust than using regular expressions that may fail on poorly formed HTML.  I've seen many people recommend Beautiful Soup, but I've had a few problems using it.  For one, it picked up unwanted text, such as JavaScript source.  Also, it did not interpret HTML entities.  For example, I would expect &amp;#39; in HTML source to be converted to an apostrophe in text, just as if I'd pasted the browser content into notepad.

Update <code>html2text</code> looks promising. It handles HTML entities correctly and ignores JavaScript.  However, it does not exactly produce plain text; it produces markdown that would then have to be turned into plain text. It comes with no examples or documentation, but the code looks clean.



Related questions:


Filter out HTML tags and resolve entities in python
Convert XML/HTML Entities into Unicode String in Python

"
332289|"How do you change the size of figures drawn with matplotlib?"|"How do you change the size of figure drawn with matplotlib?
"
338768|"Python error ""ImportError: No module named"""|"Python is installed in a local directory.  

My directory tree looks like this:

<code>(local directory)/site-packages/toolkit/interface.py
</code>

My code is in here:

<code>(local directory)/site-packages/toolkit/examples/mountain.py
</code>

To run the example, I write <code>python mountain.py</code>, and in the code I have:

<code>from toolkit.interface import interface
</code>

And I get the error:

<code>Traceback (most recent call last):
  File ""mountain.py"", line 28, in ?
    from toolkit.interface import interface
ImportError: No module named toolkit.interface
</code>

I have already checked <code>sys.path</code> and there I have the directory <code>/site-packages</code>. Also, I have the file <code>__init__.py.bin</code> in the toolkit folder to indicate to Python that this is a package. I also have a <code>__init__.py.bin</code> in the examples directory.

I do not know why Python cannot find the file when it is in <code>sys.path</code>.  Any ideas?  Can it be a permissions problem?  Do I need some execution permission?
"
339007|"Nicest way to pad zeroes to string"|"What is the most pythonic way to pad a numeric string with zeroes to the left, i.e., so the numeric string has a specific length?
"
348196|"Creating a list of objects in Python"|"I'm trying to create a Python script that opens several databases and compares their contents.  In the process of creating that script, I've run into a problem in creating a list whose contents are objects that I've created.

I've simplified the program to its bare bones for this posting. First I create a new class, create a new instance of it, assign it an attribute and then write it to a list.  Then I assign a new value to the instance and again write it to a list... and again and again...

Problem is, it's always the same object so I'm really just changing the base object.  When I read the list, I get a repeat of the same object over and over.  

So how do you write objects to a list within a loop?

Thanks,

Bob J

Here's my simplified code

<code>class SimpleClass(object):
    pass

x = SimpleClass
# Then create an empty list
simpleList = []
#Then loop through from 0 to 3 adding an attribute to the instance 'x' of SimpleClass
for count in range(0,4):       
    # each iteration creates a slightly different attribute value, and then prints it to
# prove that step is working
# but the problem is, I'm always updating a reference to 'x' and what I want to add to
# simplelist is a new instance of x that contains the updated attribute

x.attr1= '*Bob* '* count
print ""Loop Count: %s Attribute Value %s"" % (count, x.attr1)
simpleList.append(x)

print '-'*20
# And here I print out each instance of the object stored in the list 'simpleList'
# and the problem surfaces.  Every element of 'simpleList' contains the same      attribute value

y = SimpleClass
print ""Reading the attributes from the objects in the list""
for count in range(0,4):
    y = simpleList[count]
    print y.attr1
</code>

So how do I (append, extend, copy or whatever) the elements of simpleList so that each entry contains a different instance of the object instead of all pointing to the same one?
"
354038|"How do I check if a string is a number (float)?"|"What is the best possible way to check if a string can be represented as a number in Python? 

The function I currently have right now is:

<code>def is_number(s):
    try:
        float(s)
        return True
    except ValueError:
        return False
</code>

Which, not only is ugly and slow, seems clunky. However I haven't found a better method because calling <code>float</code> in the main function is even worse. 
"
354883|"How do you return multiple values in Python?"|"The canonical way to return multiple values in languages that support it is often tupling. 

Option: Using a tuple

Consider this trivial example:

<code>def f(x):
  y0 = x + 1
  y1 = x * 3
  y2 = y0 ** y3
  return (y0,y1,y2)
</code>

However, this quickly gets problematic as the number of values returned increases. What if you want to return four or five values? Sure, you could keep tupling them, but it gets easy to forget which value is where. It's also rather ugly to unpack them wherever you want to receive them.

Option: Using a dictionary

The next logical step seems to be to introduce some sort of 'record notation'. In python, the obvious way to do this is by means of a <code>dict</code>. 

Consider the following:

<code>def g(x):
  y0 = x + 1
  y1 = x * 3
  y2 = y0 ** y3
  return {'y0':y0, 'y1':y1 ,'y2':y2 }
</code>

(edit- Just to be clear, y0, y1 and y2 are just meant as abstract identifiers. As pointed out, in practice you'd use meaningful identifiers)

Now, we have a mechanism whereby we can project out a particular member of the returned object. For example, 

<code>result['y0']
</code>

Option: Using a class

However, there is another option. We could instead return a specialized structure. I've framed this in the context of Python, but I'm sure it applies to other languages as well. Indeed, if you were working in C this might very well be your only option. Here goes:

<code>class ReturnValue(object):
  def __init__(self, y0, y1, y2):
     self.y0 = y0
     self.y1 = y1
     self.y2 = y2

def g(x):
  y0 = x + 1
  y1 = x * 3
  y2 = y0 ** y3
  return ReturnValue(y0, y1, y2)
</code>

In python the previous two are perhaps very similar in terms of plumbing- After all <code>{ y0, y1, y2 }</code> just end up being entries in the internal <code>__dict__</code> of the <code>ReturnValue</code>.

There is one additional feature provided by Python though for tiny objects, the <code>__slots__</code> attribute. The class could be expressed as:

<code>class ReturnValue(object):
  __slots__ = [""y0"", ""y1"", ""y2""]
  def __init__(self, y0, y1, y2):
     self.y0 = y0
     self.y1 = y1
     self.y2 = y2
</code>

From the Python Reference Manual:


  The <code>__slots__</code> declaration takes a sequence of instance variables and reserves just enough space in each instance to hold a value for each variable. Space is saved because <code>__dict__</code> is not created for each instance.


Option: Using a list

Another suggestion which I'd overlooked comes from Bill the Lizard:

<code>def h(x):
  result = [x + 1]
  result.append(x * 3)
  result.append(y0 ** y3)
  return result
</code>

This is my least favorite method though. I suppose I'm tainted by exposure to Haskell, but the idea of mixed-type lists has always felt uncomfortable to me. In this particular example the list is -not- mixed type, but it conceivably could be. A list used in this way really doesn't gain anything with respect to the tuple as far as I can tell. The only real difference between lists and tuples in Python is that lists are mutable, wheras tuples are not. I personally tend to carry over the conventions from functional programming: use lists for any number of elements of the same type, and tuples for a fixed number of elements of predetermined types.

Question

After the lengthy preamble, comes the inevitable question. Which method (do you think) is best?

I've typically found myself going the dictionary route because it involves less set-up work. From a types perspective however, you might be better off going the class route, since that may help you avoid confusing what a dictionary represents. On the other hand, there are some in the Python community that feel implied interfaces should be preferred to explicit interfaces, at which point the type of the object really isn't relevant, since you're basically relying on the convention that the same attribute will always have the same meaning. 

So, how do -you- return multiple values in Python?
"
364621|"How to get item's position in a list?"|"I am iterating over a list and I want to print out the index of the item if it meets a certain condition. How would I do this?

Example:  

<code>testlist = [1,2,3,5,3,1,2,1,6]
for item in testlist:
    if item == 1:
        print position
</code>
"
372042|"Difference between abstract class and interface in Python"|"What is the difference between abstract class and interface in Python?
"
372885|"How do I connect to a MySQL Database in Python?"|"How do I connect to a MySQL database using a python program?
"
378927|"What is the best (idiomatic) way to check the type of a Python variable?"|"I need to know if a variable in Python is a string or a dict.  Is there anything wrong with the following code?

<code>if type(x) == type(str()):
    do_something_with_a_string(x)
elif type(x) == type(dict()):
    do_somethting_with_a_dict(x)
else:
    raise ValueError
</code>

Update: I accepted avisser's answer (though I will change my mind if someone explains why <code>isinstance</code> is preferred over <code>type(x) is</code>).

But thanks to nakedfanatic for reminding me that it's often cleaner to use a dict (as a case statement) than an if/elif/else series.

Let me elaborate on my use case.  If a variable is a string, I need to put it in a list.  If it's a dict, I need a list of the unique values.  Here's what I came up with:

<code>def value_list(x):
    cases = {str: lambda t: [t],
             dict: lambda t: list(set(t.values()))}
    try:
        return cases[type(x)](x)
    except KeyError:
        return None
</code>

If <code>isinstance</code> is preferred, how would you write this <code>value_list()</code> function?
"
379906|"Parse String to Float or Int"|"In Python, how can I parse a numeric string like <code>""545.2222""</code> to its corresponding float value, <code>542.2222</code>? Or parse the string <code>""31""</code> to an integer, <code>31</code>?

I just want to know how to parse a float string to a float, and (separately) an int string to an int.
"
394809|"Does Python have a ternary conditional operator?"|"If Python does not have a ternary conditional operator, is it possible to simulate one using other language constructs?
"
402504|"How to determine a variable's type?"|"How do I see the type of a variable whether it is unsigned 32 bit, signed 16 bit, etc.?

How do I view it?
"
403421|"How to sort a list of objects , based on an attribute of the objects?"|"I've got a list of Python objects that I'd like to sort by an attribute of the objects themselves.  The list looks like:

<code>&gt;&gt;&gt; ut
[&lt;Tag: 128&gt;, &lt;Tag: 2008&gt;, &lt;Tag: &lt;&gt;, &lt;Tag: actionscript&gt;, &lt;Tag: addresses&gt;,
 &lt;Tag: aes&gt;, &lt;Tag: ajax&gt; ...]
</code>

Each object has a count:

<code>&gt;&gt;&gt; ut[1].count
1L
</code>

I need to sort the list by number of counts descending.

I've seen several methods for this, but I'm looking for best practice in Python.
"
415511|"How to get current time in Python"|"What is the module/method used to get current time?
"
419163|"What does if __name__ == ""__main__"": do?"|"What does the <code>if __name__ == ""__main__"":</code> do?

<code># Threading example
import time, thread

def myfunction(string, sleeptime, lock, *args):
    while 1:
        lock.acquire()
        time.sleep(sleeptime)
        lock.release()
        time.sleep(sleeptime)
if __name__ == ""__main__"":
    lock = thread.allocate_lock()
    thread.start_new_thread(myfunction, (""Thread #: 1"", 2, lock))
    thread.start_new_thread(myfunction, (""Thread #: 2"", 2, lock))
</code>
"
423379|"Using global variables in a function other than the one that created them"|"If I create a global variable in one function, how can I use that variable in another function?
Do I need to store the global variable in a local variable of the function which needs its access?
"
431684|"How do I ""cd"" in Python?"|"<code>cd</code> as in the shell command to change the working directory.

How do I change the current working directory in Python?
"
432112|"Is there a Numpy function to return the first index of something in an array?"|"I know there is a method for python list to return the first index of something

<code>&gt;&gt;&gt; l = list(1, 2, 3)
&gt;&gt;&gt; l.index(2)
1
</code>

Is there something like that for numpy arrays?
"
432842|"How do you get the logical xor of two variables in Python?"|"How do you get the logical xor of two variables in Python?

For example, I have two variables that I expect to be strings. I want to test that only one of them contains a True value (is not None or the empty string):

<code>str1 = raw_input(""Enter string one:"")
str2 = raw_input(""Enter string two:"")
if logical_xor(str1, str2):
    print ""ok""
else:
    print ""bad""
</code>

The <code>^</code> operator seems to be bitwise, and not defined on all objects:

<code>&gt;&gt;&gt; 1 ^ 1
0
&gt;&gt;&gt; 2 ^ 1
3
&gt;&gt;&gt; ""abc"" ^ """"
Traceback (most recent call last):
  File ""&lt;stdin&gt;"", line 1, in &lt;module&gt;
TypeError: unsupported operand type(s) for ^: 'str' and 'str'
</code>
"
437589|"How do I unload (reload) a Python module?"|"I have a long-running Python server and would like to be able to upgrade a service without restarting the server. What's the best way do do this?

<code>if foo.py has changed:
    unimport foo  &lt;-- How do I do this?
    import foo
    myfoo = foo.Foo()
</code>
"
441147|"How can I subtract a day from a Python date?"|"I have a Python <code>datetime.datetime</code> object. What is the best way to subtract one day?
"
446052|"How can I check for Python version in a program that uses new language features?"|"If I have a Python script that requires at least a particular
version of Python, what is the correct way to fail gracefully
when an earlier version of Python is used to launch the script?

How do I get control early enough to issue an error message
and exit?

For example, I have a program that uses the ternery operator (new in 2.5) and ""with"" blocks
(new in 2.6).  I wrote a simple little interpreter-version
checker routine which is the first thing the script would
call ... except it doesn't get that far. Instead, the
script fails during python compilation, before my routines
are even called. Thus the user of the script sees some very
obscure synax error tracebacks - which pretty much require
an expert to deduce that it is simply the case of running
the wrong version of Python.

I know how to check the version of Python. The issue is that some syntax is illegal in older versions of Python. Consider this program:

<code>import sys
if sys.version_info &lt; (2, 4):
    raise ""must use python 2.5 or greater""
else:
    # syntax error in 2.4, ok in 2.5
    x = 1 if True else 2
    print x
</code>

When run under 2.4, I want this result

<code>$ ~/bin/python2.4 tern.py 
must use python 2.5 or greater
</code>

and not this result:

<code>$ ~/bin/python2.4 tern.py 
  File ""tern.py"", line 5
    x = 1 if True else 2
           ^
SyntaxError: invalid syntax
</code>

(Channeling for a coworker.)
"
448271|"What is __init__.py for?"|"What is <code>__init__.py</code> for in a Python source directory?
"
449560|"How do I determine the size of an object in Python?"|"In C, we can find the size of an <code>int</code>, <code>char</code>, etc. I want to know how to get size of objects like a string, integer, etc. in Python.

Related question: How many bytes per element are there in a Python list (tuple)?

I am using an XML file which contains size fields that specify the size of value. I must parse this XML and do my coding. When I want to change the value of a particular field, I will check the size field of that value. Here I want to compare whether the new value that I'm gong to enter is of the same size as in XML. I need to check the size of new value. In case of a string I can say its the length. But in case of int, float, etc. I am confused.
"
450285|"Executing command line programs from within python"|"
  Possible Duplicate:
  Calling an external command in Python  




I'm building a web application that will is going to manipulate (pad, mix, merge etc) sound files and I've found that sox does exactly what I want. Sox is a linux command line program and I'm feeling a little uncomfortable with having the python web app starting new sox processes on my server on a per request basis. 

Example:

<code>import os
os.system('sox input.wav -b 24 output.aiff rate -v -L -b 90 48k')
</code>

This whole setup seems a little unstable to me.

So my question is, what's the best practice for running command line programs from within  a python (or any scripting language) web app?

Message queues would be one thing to implement in order to get around the whole request response cycle. But is there other ways to make these things more elegant?
"
454854|"No module named MySQLdb"|"I am using Python version 2.5.4 and install MySQL version 5.0 and Django. Django is working fine with Python, but not MySQL. I am using it in Windows Vista.
"
455612|"Limiting floats to two decimal points"|"I want <code>a</code> to be rounded to 13.95.

<code>&gt;&gt;&gt; a
13.949999999999999
&gt;&gt;&gt; round(a, 2)
13.949999999999999
</code>

The <code>round</code> function does not work the way I expected.
"
464864|"How to get all possible combinations of a list’s elements?"|"I have a list with 15 numbers in, and I need to write some code that produces all 32,768 combinations of those numbers. 

I've found some code (by Googling) that apparently does what I'm looking for, but I found the code fairly opaque and am wary of using it. Plus I have a feeling there must be a more elegant solution.

The only thing that occurs to me would be to just loop through the decimal integers 1–32768 and convert those to binary, and use the binary representation as a filter to pick out the appropriate numbers. 

Does anyone know of a better way? Using <code>map()</code>, maybe?
"
466345|"Converting string into datetime"|"Short and simple. I've got a huge list of date-times like this as strings:

<code>Jun 1 2005  1:33PM
Aug 28 1999 12:00AM
</code>

I'm going to be shoving these back into proper datetime fields in a database so I need to magic them into real datetime objects. 

Any help (even if it's just a kick in the right direction) would be appreciated.

Edit: This is going through Django's ORM so I can't use SQL to do the conversion on insert.
"
473099|"Check if a given key already exists in a dictionary and increment it"|"Given a dictionary, how can I find out if a given key in that dictionary has already been set to a non-None value?

I.e., I want to do this:

<code>my_dict = {}

if (my_dict[key] != None):
  my_dict[key] = 1
else:
  my_dict[key] += 1
</code>

I.e., I want to increment the value if there's already one there, or set it to 1 otherwise.
"
477486|"How to use a decimal range() step value?"|"Is there a way to step between 0 and 1 by 0.1? 

I thought I could do it like the following, but it failed:

<code>for i in range(0, 1, 0.1):
    print i
</code>

Instead, it says that the step argument cannot be zero, which I did not expect.
"
480214|"How do you remove duplicates from a list in whilst preserving order?"|"Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:

<code>def uniq(input):
  output = []
  for x in input:
    if x not in output:
      output.append(x)
  return output
</code>

(Thanks to unwind for that code sample.)

But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.

Related question: In Python, what is the fastest algorithm for removing duplicates from a list so that all elements are unique while preserving order?
"
491921|"Unicode (UTF-8) reading and writing to files in Python"|"I'm having some brain failure in understanding reading and writing text to a file (Python 2.4).

<code># The string, which has an a-acute in it.
ss = u'Capit\xe1n'
ss8 = ss.encode('utf8')
repr(ss), repr(ss8)
</code>


  (""u'Capit\xe1n'"", ""'Capit\xc3\xa1n'"")


<code>print ss, ss8
print &gt;&gt; open('f1','w'), ss8

&gt;&gt;&gt; file('f1').read()
'Capit\xc3\xa1n\n'
</code>

So I type in <code>Capit\xc3\xa1n</code> into my favorite editor, in file f2.

Then:

<code>&gt;&gt;&gt; open('f1').read()
'Capit\xc3\xa1n\n'
&gt;&gt;&gt; open('f2').read()
'Capit\\xc3\\xa1n\n'
&gt;&gt;&gt; open('f1').read().decode('utf8')
u'Capit\xe1n\n'
&gt;&gt;&gt; open('f2').read().decode('utf8')
u'Capit\\xc3\\xa1n\n'
</code>

What am I not understanding here? Clearly there is some vital bit of magic (or good sense) that I'm missing. What does one type into text files to get proper conversions?

What I'm truly failing to grok here, is what the point of the UTF-8 representation is, if you can't actually get Python to recognize it, when it comes from outside. Maybe I should just JSON dump the string, and use that instead, since that has an asciiable representation! More to the point, is there an ASCII representation of this Unicode object that Python will recognize and decode, when coming in from a file?  If so, how do I get it?

<code>&gt;&gt;&gt; print simplejson.dumps(ss)
'""Capit\u00e1n""'
&gt;&gt;&gt; print &gt;&gt; file('f3','w'), simplejson.dumps(ss)
&gt;&gt;&gt; simplejson.load(open('f3'))
u'Capit\xe1n'
</code>
"
492387|"IndentationError: unindent does not match any outer indentation level"|"When I compile the Python code below, I get 


  IndentationError: unindent does not match any outer indentation level




<code>import sys

def Factorial(n): # Return factorial
    result = 0
    for i in range (1,n):
        result = result * i
    print ""factorial is "",result
    return result
</code>

Why?
"
493386|"How to print without newline or space?"|"The question is in the title.

I'd like to do in  python what I do in this example in c:

<code>#include &lt;stdio.h&gt;

int main() {
    int i;
    for (i=0; i&lt;10; i++) printf(""."");
    return 0;
}
</code>

Output:

<code>..........
</code>

In Python:

<code>&gt;&gt;&gt; for i in xrange(0,10): print '.'
.
.
.
.
.
.
.
.
.
.
&gt;&gt;&gt; for i in xrange(0,10): print '.',
. . . . . . . . . .
</code>

In Python <code>print</code> will add a <code>\n</code> or a space, how can I avoid that? Now, it's just an example. Don't tell me I can first build a string then print it. I'd like to know how to ""append"" strings to <code>stdout</code>.
"
493819|"Python join: why is it string.join(list) instead of list.join(string)?"|"This has always confused me. It seems like this would be nicer:

<code>my_list = [""Hello"", ""world""]
print my_list.join(""-"")
# Produce: ""Hello-world""
</code>

Than this:

<code>my_list = [""Hello"", ""world""]
print ""-"".join(my_list)
# Produce: ""Hello-world""
</code>

Is there a specific reason it is like this?
"
494594|"How to write the Fibonacci Sequence in Python"|"I had originally coded the program wrongly. Instead of returning the Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 should = only those numbers between 1 &amp; 20), I have written for the program to display all Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 displays = First 20 Fibonacci numbers). I thought I had a sure-fire code. I also do not see why this is happening.

<code>startNumber = int(raw_input(""Enter the start number here ""))
endNumber = int(raw_input(""Enter the end number here ""))

def fib(n):
    if n &lt; 2:
        return n
    return fib(n-2) + fib(n-1)

print map(fib, range(startNumber, endNumber))
</code>

Someone pointed out in my Part II (which was closed for being a duplicate - https://stackoverflow.com/questions/504193/how-to-write-the-fibonacci-sequence-in-python-part-ii) that I need to pass the startNumber and endNumber through a generator using a while loop. Can someone please point me in the direction on how to do this? Any help is welcome.



I'm a learning programmer and I've run into a bit of a jumble. I am asked to write a program that will compute and display Fibonacci's Sequence by a user inputted start number and end number (ie. startNumber = 20 endNumber = 100 and it will display only the numbers between that range). The trick is to use it inclusively (which I do not know how to do in Python? - I'm assuming this means to use an inclusive range?).

What I have so far is no actual coding but rather:


Write Fib sequence formula to infinite
Display startNumber to endNumber only from Fib sequence.


I have no idea where to start and I am asking for ideas or insight into how to write this. I also have tried to write the Fib sequence forumla but I get lost on that as well.
"
509211|"Explain slice notation"|"I need a good explanation (references are a plus) on Python's slice notation. 

To me, this notation needs a bit of picking up. 

It looks extremely powerful, but I haven't quite got my head around it.
"
510348|"How can I make a time delay in Python?"|"I would like to know how to put a time delay in a Python script.
"
510972|"Getting the class name of an instance in Python"|"How do I find out a name of class that created an instance of an object in Python if the function I am doing this from is the base class of which the class of the instance has been derived?

Was thinking maybe the inspect module might have helped me out here, but it doesn't seem to give me what I want. And short of parsing the <code>__class__</code> member, I'm not sure how to get at this information.
"
517970|"How to clear the interpreter console?"|"Like most Python developers, I typically keep a console window open with the Python interpreter running to test commands, dir() stuff, help() stuff, etc.

Like any console, after a while the visible backlog of past commands and prints gets to be cluttered, and sometimes confusing when re-running the same command several times.  I'm wondering if, and how, to clear the Python interpreter console.

I've heard about doing a system call and either calling <code>cls</code> on Windows or <code>clear</code> on Linux, but I was hoping there was something I could command the interpreter itself to do.

Note: I'm running on Windows, so Ctrl+L doesn't work.
"
518021|"Getting the length of an array in Python"|"In Python, is the following the only way to get the number of elements?

<code>arr.__len__()
</code>

If so, why the strange syntax?
"
521674|"Initializing a list to a known number of elements in Python"|"Right now I am using a list, and was expecting something like:

<code>verts = list (1000)
</code>

Should I use array instead?
"
522563|"Accessing the index in Python 'for' loops"|"How do I access the index itself for a list like the following?

<code>ints = [8, 23, 45, 12, 78]
</code>

When I loop through it using a <code>for</code> loop, how do I access the loop index, from 1 to 5 in this case?
"
525592|"Find and Replace Inside a Text File from a Bash Command"|"What's the simplest way to do a find and replace for a given input string, say <code>abc</code>, and replace with another string, say <code>XYZ</code> in file <code>/tmp/file.txt</code>?

I am writting an app and using IronPython to execute commands through SSH &mdash; but I don't know Unix that well and don't know what to look for.

I have heard that Bash, apart from being a command line interface, can be a very powerful scripting language. So, if this is true, I assume you can perform actions like these.

Can I do it with bash, and what's the simplest (one line) script to achieve my goal?
"
529424|"Traverse a list in reverse order in Python"|"So I can start from <code>len(collection)</code> and end in <code>collection[0]</code>.

EDIT: Sorry, I forgot to mention I also want to be able to access the loop index.
"
538346|"Iterating over a string"|"In C++, I could do:

<code>for (int i = 0; i &lt; str.length(); ++i)
    std::cout &lt;&lt; str[i] &lt;&lt; std::endl;
</code>

How do I iterate over a string in Python?
"
541390|"Extracting extension from filename in Python"|"Is there a function to extract the extension from a filename?
"
543309|"Programmatically stop execution of python script?"|"
  Possible Duplicate:
  Terminating a Python script  




Is it possible to stop execution of a python script at any line with a command?

Like

<code>some code

quit() # quit at this point

some more code (that's not executed)
</code>
"
568962|"How do I create an empty array/matrix in NumPy?"|"I can't figure out how to use an array or matrix in the way that I would normally use a list. I want to create an empty array (or matrix) and then add one column (or row) to it at a time.

At the moment the only way I can find to do this is like:

<code>mat = None
for col in columns:
    if mat is None:
        mat = col
    else:
        mat = hstack((mat, col))
</code>

Whereas if it were a list, I'd do something like this:

<code>list = []
for item in data:
    list.append(item)
</code>

Is there a way to use that kind of notation for NumPy arrays or matrices?
"
574730|"Python: How to ignore an exception and proceed?"|"I have a try...except block in my code and When an exception is throw. I really just want to continue with the code because in that case, everything is still able to run just fine. The problem is if you leave the except: block empty or with a #do nothing, it gives you a syntax error. I can't use continue because its not in a loop. Is there a keyword i can use that tells the code to just keep going?
"
576169|"Understanding Python super() with __init__() methods"|"I'm trying to understand <code>super()</code>. From the looks of it, both child classes can be created just fine. I'm curious as to what difference there actually is between the following child classes:

<code>class Base(object):
    def __init__(self):
        print ""Base created""

class ChildA(Base):
    def __init__(self):
        Base.__init__(self)

class ChildB(Base):
    def __init__(self):
        super(ChildB, self).__init__()

ChildA() 
ChildB()
</code>
"
582336|"How can you profile a script?"|"Project Euler and other coding contests often have a maximum time to run or people boast of how fast their particular solution runs.  With python, sometimes the approaches are somewhat kludgey - i.e., adding timing code to <code>__main__</code>.

What is a good way to profile how long a python program takes to run?
"
600268|"mkdir -p functionality in Python"|"Is there a way to get functionality similar to <code>mkdir -p</code> on the shell from within Python.  I am looking for a solution other than a system call.  I am sure the code is less than 20 lines, and I am wondering if someone has already written it?
"
604802|"Python: finding an element in an array"|"What is a good way to find the index of an element in an array in python? 
Note that the array may not be sorted.
Is there a way to specify what comparison operator to use?
"
606191|"Convert bytes to a Python string"|"I'm using this code to get standard output from an external program:

<code>&gt;&gt;&gt; from subprocess import *
&gt;&gt;&gt; command_stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0]
</code>

The communicate() method returns an array of bytes:

<code>&gt;&gt;&gt; command_stdout
b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2\n'
</code>

However, I'd like to work with the output as a normal Python string. So that I could print it like this:

<code>&gt;&gt;&gt; print(command_stdout)
-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1
-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2
</code>

I thought that's what the binascii.b2a_qp() method is for, but when I tried it, I got the same byte array again:

<code>&gt;&gt;&gt; binascii.b2a_qp(command_stdout)
b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2\n'
</code>

Does anybody know how to convert the bytes value back to string? I mean, using the ""batteries"" instead of doing it manually. And I'd like it to be ok with Python 3.
"
610883|"How to know if an object has an attribute in Python"|"Is there a way in Python to determine if an object has some attribute?  For example:

<code>&gt;&gt;&gt; a = SomeClass()
&gt;&gt;&gt; a.someProperty = value
&gt;&gt;&gt; a.property
Traceback (most recent call last):
  File ""&lt;stdin&gt;"", line 1, in &lt;module&gt;
AttributeError: SomeClass instance has no attribute 'property'
</code>

How can you tell if <code>a</code> has the attribute <code>property</code> before using it?
"
613183|"Sort a Python dictionary by value"|"I have a dictionary of values read from two fields in a database: a string field and a numeric field. The string field is unique, so that is the key of the dictionary.

I can sort on the keys, but how can I sort based on the values?

Note: I have read Stack Overflow question How do I sort a list of dictionaries by values of the dictionary in Python? and probably could change my code to have a list of dictionaries, but since I do not really need a list of dictionaries I wanted to know if there is a simpler solution.
"
625083|"Python __init__ and self what do they do?"|"I'm learning the Python programming language and I've came across something I don't fully understand. 

In a method like:

<code>def method(self, blah):
    def __init__(?):
        ....
    ....
</code>

What does <code>self</code> do?  What is it meant to be?  Is it mandatory?

What does the <code>__init__</code> method do?  Why is it necessary? (etc.)

I think they might be OOP constructs, but I don't know very much.
"
626759|"What's the difference between lists and tuples?"|"What's the difference?

What are the advantages / disadvantages of tuples / lists?
"
627435|"How to remove an element from a list by index in Python?"|"How to remove an element from a list by index in Python?

I found the <code>list.remove</code> method, but say I want to remove the last element, how do I do this? It seems like the default remove searches the list, but I don't want any search to be performed.
"
642154|"How to convert strings into integers in Python?"|"I have a tuple of tuples from a MySQL query like this:

<code>T1 = (('13', '17', '18', '21', '32'),
      ('07', '11', '13', '14', '28'),
      ('01', '05', '06', '08', '15', '16'))
</code>

I'd like to convert all the string elements into integers and put them back into a list of lists:

<code>T2 = [[13, 17, 18, 21, 32], [7, 11, 13, 14, 28], [1, 5, 6, 8, 15, 16]]
</code>

I tried to achieve it with <code>eval</code> but didn't get any decent result yet.
"
642763|"Find intersection of two lists?"|"I know how to get an intersection of two flat lists:

<code>b1 = [1,2,3,4,5,9,11,15]
b2 = [4,5,6,7,8]
b3 = [val for val in b1 if val in b2]
</code>

or 

<code>def intersect(a, b):
    return list(set(a) &amp; set(b))

print intersect(b1, b2)
</code>

But when I have to find intersection for nested lists then my problems starts:

<code>c1 = [1, 6, 7, 10, 13, 28, 32, 41, 58, 63]
c2 = [[13, 17, 18, 21, 32], [7, 11, 13, 14, 28], [1, 5, 6, 8, 15, 16]]
</code>

In the end I would like to receive:

<code>c3 = [[13,32],[7,13,28],[1,6]]
</code>

Can you guys give me a hand with this?

Related


Flattening a shallow list in python

"
645312|"What is the quickest way to HTTP GET in Python?"|"What is the quickest way to HTTP GET in Python if I know the content will be a string? I am searching the docs for a quick one-liner like:

<code>contents = url.get(""http://example.com/foo/bar"")
</code>

But all I can find using Google are <code>httplib</code> and <code>urllib</code> - and I am unable to find a shortcut in those libraries.

Does standard Python 2.5 have a shortcut in some form as above, or should I write a function <code>url_get</code>?


I would prefer not to capture the output of shelling out to <code>wget</code> or <code>curl</code>.

"
663171|"Is there a way to substring a string in Python?"|"Is there a way to substring a string in Python, to get a new string from the 3rd character to the end of the string?

Maybe like <code>myString[2:end]</code>?

If leaving the second part means 'till the end', if you leave the first part, does it start from the start?
"
664294|"Is it possible only to declare a variable without assigning any value in Python?"|"Is it possible to declare a variable in Python, like so?:

<code>var
</code>

so that it initialized to None? It seems like Python allows this, but as soon as you access it, it crashes. Is this possible? If not, why?

EDIT: I want to do this for cases like this:

<code>value

for index in sequence:

   if value == None and conditionMet:
       value = index
       break
</code>

Duplicate


Uninitialised value in python (by same author)
Are there any declaration keywords in Python? (by the same author)


Related


Python: variable scope and function calls
Other languages have ""variables""

"
672172|"Using python map and other functional tools"|"This is quite n00bish, but I'm trying to learn/understand functional programming in python. The following code:

<code>foos = [1.0,2.0,3.0,4.0,5.0]
bars = [1,2,3]

def maptest(foo, bar):
    print foo, bar

map(maptest, foos, bars)
</code>

produces:

<code>1.0 1
2.0 2
3.0 3
4.0 None
5.0 None
</code>

Q. Is there a way to use map or any other functional tools in python to produce the following without loops etc.

<code>1.0 [1,2,3]
2.0 [1,2,3]
3.0 [1,2,3]
4.0 [1,2,3]
5.0 [1,2,3]
</code>

Just as a side note how would the implementation change if there is a dependency between foo and bar. e.g.

<code>foos = [1.0,2.0,3.0,4.0,5.0]
bars = [1,2,3,4,5]
</code>

and print:

<code>1.0 [2,3,4,5]
2.0 [1,3,4,5]
3.0 [1,2,4,5]
...
</code>

P.S: I know how to do it naively using if, loops and/or generators, but I'd like to learn how to achieve the same using functional tools. Is it just a case of adding an if statement to maptest or apply another filter map to bars internally within maptest?
"
674764|"Examples for string find in Python"|"I am trying to find some examples but no luck. Does anyone know of some examples on the net? I would like to know what it returns when it can't find, and how to specify from start to end, which I guess is going to be 0, -1.
"
675442|"Comment out a Python code block"|"Is there a mechanism to comment out large blocks of Python code?

Right now, the only ways I can see of commenting out code are to either start every line with a <code>#</code>, or to enclose the code in triple quotes: <code>""""""</code>.

The problem with these is that inserting <code>#</code> before every line is cumbersome and <code>""""""</code> makes the string I want to use as a comment show up in generated documentation.

After reading all comments, the answer seems to be ""No"".
"
676172|"Full examples of using pySerial package"|"Can someone please show me a full python sample code that uses pyserial, i have the package and am wondering how to send the AT commands and read them back!
"
678236|"How to get the filename without the extension from a path in Python?"|"How to get the filename without the extension from a path in Python?

I found out a method called <code>os.path.basename</code> to get the filename with extension. But even when I import os, I am not able to call it <code>path.basename</code>. Is it possible to call it as directly as basename?
"
699866|"Python int to binary?"|"Are there any canned Python methods to convert an Integer (or Long) into a binary string in Python?

There are a myriad of dec2bin() functions out on Google... But I was hoping I could use a built-in function / library.
"
704152|"How can I convert a character to a integer in Python, and viceversa?"|"I want to get, given a character, its <code>ASCII</code> value.

For example, for the character <code>a</code>, I want to get <code>97</code>, and vice versa.
"
713847|"Recommendations of Python REST (web services) framework?"|"Is there a list somewhere of recommendations of different Python-based REST frameworks for use on the serverside to write your own RESTful APIs? Preferably with pros and cons.

Please feel free to add recommendations here. :)
"
714063|"Importing modules from parent folder"|"I am running Python 2.5.

This is my folder tree:

<code>ptdraft/
  nib.py
  simulations/
    life/
      life.py
</code>

(I also have <code>__init__.py</code> in each folder, omitted here for readability)

How do I import the <code>nib</code> module from inside the <code>life</code> module? I am hoping it is possible to do without tinkering with sys.path.

Note: The main module being run is in the <code>ptdraft</code> folder.
"
715417|"Converting from a string to boolean in Python?"|"Does anyone know how to do convert from a string to a boolean in Python? I found this link. But it doesn't look like a proper way to do it.  I.e. using a built in functionality, etc.

EDIT:

The reason I asked this is because I learned <code>int(""string"")</code>, from here. I tried <code>bool(""string"")</code> but always got <code>True</code>.

<code>&gt;&gt;&gt; bool(""False"")
True
</code>
"
730764|"Try/Except in Python: How do you properly ignore Exceptions?"|"When you just want to do a try-except without handling the exception, how do you do it in Python?

Is the following the right way to do it?

<code>try:
    shutil.rmtree(path)
except:
    pass
</code>
"
733454|"Best way to format integer as string with leading zeros?"|"I need to add leading zeros to integer to make a string with defined quantity of digits ($cnt).
What the best way to translate this simple function from PHP to Python:

<code>function add_nulls($int, $cnt=2) {
    $int = intval($int);
    for($i=0; $i&lt;($cnt-strlen($int)); $i++)
        $nulls .= '0';
    return $nulls.$int;
}
</code>

Is there a function that can do this?
"
735975|"Static methods in Python?"|"Is it possible to have static methods in Python so I can call them without initializing a class, like:

<code>ClassName.StaticMethod ( )
</code>
"
739654|"How to make a chain of function decorators?"|"How can I make two decorators in Python that would do the following?

<code>@makebold
@makeitalic
def say():
   return ""Hello""
</code>

...which should return:

<code>""&lt;b&gt;&lt;i&gt;Hello&lt;/i&gt;&lt;/b&gt;""
</code>

I'm not trying to make <code>HTML</code> this way in a real application - just trying to understand how decorators and decorator chaining works.
"
739993|"How can I get a list of locally installed Python modules?"|"I would like to get a list of Python modules, which are in my Python installation (UNIX server).

How can you get a list of Python modules installed in your computer?
"
740287|"How to check if one of the following items is in a list?"|"I'm trying to find a short way to see if any of the following items is in a list, but my first attempt does not work. Besides writing a function to accomplish this, is the any short way to check if one of multiple items is in a list.

<code>&gt;&gt;&gt; a = [2,3,4]
&gt;&gt;&gt; print (1 or 2) in a
False
&gt;&gt;&gt; print (2 or 1) in a
True
</code>
"
743164|"Emulate a do-while loop in Python?"|"I need to emulate a do-while loop in a Python program. Unfortunately, the following straightforward code does not work:

<code>l = [ 1, 2, 3 ]
i = l.__iter__()
s = None
while True :
  if s :
    print s
  try :
    s = i.next()
  except StopIteration :
    break
print ""done""
</code>

Instead of ""1,2,3,done"", it prints the following output:

<code>[stdout:]1
[stdout:]2
[stdout:]3
None['Traceback (most recent call last):
', '  File ""test_python.py"", line 8, in &lt;module&gt;
    s = i.next()
', 'StopIteration
']
</code>

What can I do in order to catch the 'stop iteration' exception and break a while
loop properly?

An example of why such a thing may be needed is shown below as pseudocode.

State machine:

<code>s = """"
while True :
  if state is STATE_CODE :
    if ""//"" in s :
      tokens.add( TOKEN_COMMENT, s.split( ""//"" )[1] )
      state = STATE_COMMENT
    else :
      tokens.add( TOKEN_CODE, s )
  if state is STATE_COMMENT :
    if ""//"" in s :
      tokens.append( TOKEN_COMMENT, s.split( ""//"" )[1] )
    else
      state = STATE_CODE
      # Re-evaluate same line
      continue
  try :
    s = i.next()
  except StopIteration :
    break
</code>
"
743806|"How to split a string into a list?"|"I want my python function to split a sentence (input) and store each word in a list. The code that I've written so far splits the sentence, but does not store the words as a list. How do I do that?

<code>def split_line(text):

    # split the text
    words = text.split()

    # for each word in the line:
    for word in words:

        # print the word
        print(word)
</code>
"
750136|"How is returning the output of a function different than printing it?"|"In my previous question, Andrew Jaffe writes: 


  In addition to all of the other hints and tips, I think you're missing something crucial: your functions actually need to return something.
  When you create <code>autoparts()</code> or <code>splittext()</code>, the idea is that this will be a function that you can call, and it can (and should) give something back.
  Once you figure out the output that you want your function to have, you need to put it in a <code>return</code> statement.


<code>def autoparts():
    parts_dict = {}
    list_of_parts = open('list_of_parts.txt', 'r')

    for line in list_of_parts:
        k, v = line.split()
        parts_dict[k] = v

    print(parts_dict)

&gt;&gt;&gt; autoparts()
{'part A': 1, 'part B': 2, ...}
</code>

This function creates a dictionary, but it does not return something.  However, since I added the <code>print</code>, the output of the function is shown when I run the function.  What is the difference between <code>return</code>ing something and <code>print</code>ing it?
"
761804|"Trimming a string in Python"|"How do I remove leading and trailing whitespace from a string in Python?

For example:

<code>"" Hello "" --&gt; ""Hello""
"" Hello""  --&gt; ""Hello""
""Hello ""  --&gt; ""Hello""
""Bob has a cat"" --&gt; ""Bob has a cat""
</code>
"
773814|"Plot logarithmic axes with matplotlib in python"|"I want to plot a graph with one logarithmic axis using matplotlib. 

I've been reading the docs, but can't figure out the syntax. I know that it's probably something simple like 'scale=linear' in the plot arguments, but I can't seem to get it right

Sample program: 

<code>from pylab import *
import matplotlib.pyplot  as pyplot
a = [ pow(10,i) for i in range(10) ]
fig = pyplot.figure()
ax = fig.add_subplot(2,1,1)

line, = ax.plot(a, color='blue', lw=2)
show()
</code>
"
805066|"Call a parent class's method from child class in Python?"|"When creating a simple object hierarchy in Python, I'd like to be able to invoke methods of the parent class from a derived class.  In Perl and Java, there is a keyword for this (super).  In Perl, I might do this:

<code>package Foo;

sub frotz {
    return ""Bamf"";
}

package Bar;
@ISA = qw(Foo);

sub frotz {
   my $str = SUPER::frotz();
   return uc($str);
}
</code>

In python, it appears that I have to name the parent class explicitly from the child.
In the example above, I'd have to do something like Foo::frotz().  

This doesn't seem right, since this behavior makes it hard to make deep hierarchies.  If children need to know what class defined an inherited method, then all sorts of information pain is created.  

Is this an actual limitation in python, a gap in my understanding or both?
"
817087|"Call a function with argument list in python"|"I'm trying to call a function inside another function in python, but can't find the right syntax. What I want to do is something like this:

<code>def wrapper(func, args):
    func(args)

def func1(x):
    print(x)

def func2(x, y, z):
    return x+y+z

wrapper(func1, [x])
wrapper(func2, [x, y, z])
</code>

In this case first call will work, and second won't.
What I want to modify is the wrapper function and not the called functions.
"
842059|"Is there a portable way to get the current username in Python?"|"Is there a portable way to get the current user's username in Python (i.e., one that works under both Linux and Windows, at least).  It would work like <code>os.getuid</code>:

<code>&gt;&gt;&gt; os.getuid()
42
&gt;&gt;&gt; os.getusername()
'slartibartfast'
</code>

I googled around and was surprised not to find a definitive answer (although perhaps I was just googling poorly).  The pwd module provides a relatively easy way to achieve this under, say, Linux, but it is not present on Windows.  Some of the search results suggested that getting the username under Windows can be complicated in certain circumstances (e.g., running as a Windows service), although I haven't verified that.
"
843277|"How do I check if a variable exists?"|"I want to check if a variable exists. Now I'm doing something like this:

<code>try:
   myVar
except NameError:
   # Do something.
</code>

Are there other ways without exceptions?
"
845058|"How to get line count cheaply in Python?"|"I need to get a line count of a large file (hundreds of thousands of lines) in python. What is the most efficient way both memory- and time-wise?

At the moment I do:

<code>def file_len(fname):
    with open(fname) as f:
        for i, l in enumerate(f):
            pass
    return i + 1
</code>

is it possible to do any better?
"
850795|"Different ways of clearing lists"|"Is there any reason to do anything more complicated than one of these two lines when you want to clear a list in Python?

<code>old_list = []
old_list = list()
</code>

The reason I ask is that I just saw this in some running code:

<code>del old_list[ 0:len(old_list) ]
</code>
"
865115|"How do I correctly clean up a Python object?"|"<code>class Package:
    def __init__(self):
        self.files = []

    # ...

    def __del__(self):
        for file in self.files:
            os.unlink(file)
</code>

<code>__del__(self)</code> above fails with an AttributeError exception.  I understand Python doesn't guarantee the existence of ""global variables"" (member data in this context?) when <code>__del__()</code> is invoked.  If that is the case and this is the reason for the exception, how do I make sure the object destructs properly?
"
890128|"Why are Python lambdas useful?"|"I'm trying to figure out Python lambdas.  Is lambda one of those ""interesting"" language items that in real life should be forgotten? 

I'm sure there are some edge cases where it might be needed, but given the obscurity of it, the potential of it being redefined in future releases (my assumption based on the various definitions of it) and the reduced coding clarity - should it be avoided?  

This reminds me of overflowing (buffer overflow) of C types - pointing to the top variable and overloading to set the other field values.  It feels like sort of a techie showmanship but maintenance coder nightmare.
"
893162|"What's a good IDE for Python on Mac OS X?"|"I'm about to start a new job where the coding practices are heavily centered around TDD and refactoring, and whose primary development language is Python.  I come from the Java world, and have been a confident user of Eclipse for a good, long time.  When not working in Java, I use emacs.

I'm looking for an IDE for Python that will give me a lot of the capabilities I've grown used to with Eclipse, not only for refactoring but in terms of code completion, project management, SCM integration (currently CVS, but likely to switch to git one of these days) et al.

What IDE should I use?
"
899103|"Writing a list to a file with Python"|"Is this the cleanest way to write a list to a file, since <code>writelines()</code> doesn't insert newline characters?

<code>file.writelines([""%s\n"" % item  for item in list])
</code>

It seems like there would be a standard way...
"
903853|"How do you extract a column from a multi-dimensional array?"|"Does anybody know how to extract a column from a multi-dimensional array in Python?
"
919680|"Can a variable number of arguments be passed to a function?"|"In a similar way to using varargs in C or C++:

<code>fn(a, b)
fn(a, b, c, d, ...)
</code>
"
930397|"Getting the last element of a list in Python"|"In Python, how do you get the last element of a list?
"
931092|"Reverse a string in Python"|"There is no built in <code>reverse</code> function in Python's <code>str</code> object. What is the best way of implementing this?

If supplying a very concise answer, please elaborate on it's efficiency. Is the <code>str</code> converted to a different object, etc. 
"
944700|"How to check for NaN in python?"|"<code>float('nan')</code> results in Nan (not a number). But how do I check for it? Should be very easy, but I cannot find it.
"
952914|"Making a flat list out of list of lists in Python"|"I wonder whether there is a shortcut to make a simple list out of list of lists in Python.

I can do that in a for loop, but maybe there is some cool ""one-liner""? I tried it with reduce, but I get an error.

Code

<code>l = [[1, 2, 3], [4, 5, 6], [7], [8, 9]]
reduce(lambda x, y: x.extend(y), l)
</code>

Error message

<code>Traceback (most recent call last):
  File ""&lt;stdin&gt;"", line 1, in &lt;module&gt;
  File ""&lt;stdin&gt;"", line 1, in &lt;lambda&gt;
AttributeError: 'NoneType' object has no attribute 'extend'
</code>
"
954834|"How do I use raw_input in Python 3"|"<code>import sys
print (sys.platform)
print (2 ** 100)
raw_input( )
</code>

I am using Python 3.1 and can't get the raw_input to ""freeze"" the dos pop-up. The book I'm reading is for 2.5 and I'm using 3.1

What should I do to fix this?
"
960733|"Python creating a dictionary of lists"|"I want to create a dictionary whose values are lists.  For example: 

<code>{
  1: ['1'],
  2: ['1','2'],
  3: ['2']
}
</code>

If I do:

<code>d = dict()
a = ['1', '2']
for i in a:
    for j in range(int(i), int(i) + 2): 
        d[j].append(i)
</code>

I get a KeyError, because d[...] isn't a list.  In this case, I can add the following code after the assignment of a to initialize the dictionary. 

<code>for x in range(1, 4):
    d[x] = list()
</code>

Is there a better way to do this?  Lets say I don't know the keys I am going to need until I am in the second <code>for</code> loop.  For example:

<code>class relation:
    scope_list = list()
...
d = dict()
for relation in relation_list:
    for scope_item in relation.scope_list:
        d[scope_item].append(relation)
</code>

An alternative would then be replacing 

<code>d[scope_item].append(relation)
</code>

with 

<code>if d.has_key(scope_item):
    d[scope_item].append(relation)
else:
    d[scope_item] = [relation,]
</code>

What is the best way to handle this?  Ideally, appending would ""just work"".  Is there some way to express that I want a dictionary of empty lists, even if I don't know every key when I first create the list?
"
961632|"Converting integer to string in Python?"|"I want to convert an integer to a string in Python. I am typecasting it in vain:

<code>t=raw_input()
c=[]
for j in range(0,int(t)):
    n=raw_input()
    a=[]
    a,b= (int(i) for i in n.split(' '))
    d=pow(a,b)
    d.str()
    c.append(d[0])
for j in c:
    print j
</code>

When I try to convert it to string, it's showing an error like <code>int</code> doesn't have any attribute called <code>str</code>.
"
973473|"Getting a list of all subdirectories in the current directory"|"Is there a way to return a list of all the subdirectories in the current directory in Python?

I know you can do this with files, but I need to get the list of directories instead.
"
976882|"Shuffling a list of objects"|"I have a list of objects in Python and I want to shuffle them. I thought I could use the <code>random.shuffle</code> method, but this seems to fail when the list is of objects. Is there a method for shuffling object or another way around this?

<code>import random

class a:
    foo = ""bar""

a1 = a()
a2 = a()
b = [a1,a2]

print random.shuffle(b)
</code>

This will fail.
"
983354|"How do I make python to wait for a pressed key"|"I want my script to wait until the user presses any key.

How do I do that?
"
986006|"How do I pass a variable by reference?"|"The Python documentation seems unclear about whether parameters are passed by reference or value, and the following code produces the unchanged value 'Original'

<code>class PassByReference:
    def __init__(self):
        self.variable = 'Original'
        self.change(self.variable)
        print(self.variable)

    def change(self, var):
        var = 'Changed'
</code>

Is there something I can do to pass the variable by actual reference?
"
988228|"Convert a String representation of a Dictionary to a dictionary?"|"How can I convert the <code>str</code> representation of a <code>dict</code>, such as the following string, into a <code>dict</code>?

<code>s = ""{'muffin' : 'lolz', 'foo' : 'kitty'}""
</code>

I prefer not to use <code>eval</code>. What else can I use?

The main reason for this, is one of my coworkers classes he wrote, converts all input into strings. I'm not in the mood to go and modify his classes, to deal with this issue.
"
990754|"How to leave/exit/deactivate a python virtualenv?"|"I'm using virtualenv and the virtualenvwrapper. I can switch between virtualenv's just fine using the workon command. 

<code>me@mymachine:~$ workon env1
(env1)me@mymachine:~$ workon env2
(env2)me@mymachine:~$ workon env1
(env1)me@mymachine:~$ 
</code>

However, how do I exit all virtual machines and workon my real machine again? Right now, the only way I have of getting back to

<code>me@mymachine:~$ 
</code>

is to exit the shell and start a new one. That's kind of annoying. Is there a command to workon ""nothing"", and if so, what is it? If such a command does not exist, how would I go about creating it?
"
991027|"How to calculate a mod b in python?"|"Is there a modulo function in the python <code>math</code> library?

Isn't <code>15 % 4</code>, 3? But <code>15 mod 4</code> is 1, right?
"
997797|"What does %s mean in Python?"|"What does %s mean in Python? And what does the following bit of code do?

For instance... 

<code> if len(sys.argv) &lt; 2:
     sys.exit('Usage: %s database-name' % sys.argv[0])

 if not os.path.exists(sys.argv[1]):
     sys.exit('ERROR: Database %s was not found!' % sys.argv[1])
</code>
"
1009860|"Command Line Arguments In Python"|"I am originally a C programmer. I have seen numerous tricks and ""hacks"" to read many different arguments. 

What are some of the ways Python programmers can do this?

Related


What’s the best way to grab/parse command line arguments passed to a Python script?
Implementing a “[command] [action] [parameter]” style command-line interfaces?
How can I process command line arguments in Python?
How do I format positional argument help using Python’s optparse?

"
1016814|"What to do with ""Unexpected indent"" in python?"|"How do I rectify the error ""unexpected indent"" in python?
"
1024847|"Add new keys to a dictionary?"|"Is it possible to add a key to a Python dictionary after it has been created? It doesn't seem to have an <code>.add()</code> method.
"
1027714|"How to execute a file within the python interpreter?"|"I'm trying to execute a file with python commands from within the interpreter. 

EDIT: I'm trying to use variables and settings from that file, not to invoke a separate process.
"
1035340|"Reading binary file and looping over each byte"|"In Python, how do I read in a binary file and loop over each byte of that file?
"
1038824|"How do I remove a substring from the end of a string in Python?"|"I have the following code:

<code>url = 'abcdc.com'
print(url.strip('.com'))
</code>

I expected: <code>abcdc</code>

I got: <code>abcd</code>

Now I do 

<code>url.rsplit('.com', 1)
</code>

Is there a better way?
"
1059559|"Split Strings with Multiple Delimiters?"|"I think what I want to do is a fairly common task but I've found no reference on the web. I have text, with punctuation, and I want list of the words. 

<code>""Hey, you - what are you doing here!?""
</code>

should be

<code>['hey', 'you', 'what', 'are', 'you', 'doing', 'here']
</code>

But Python's <code>str.split()</code> only works with one argument... So I have all words with the punctuation after I split with whitespace. Any ideas?
"
1093322|"How do I check what version of Python is running my script?"|"How can I check what version of the Python Interpreter is interpreting my script?
"
1098549|"Proper way to use **kwargs in Python"|"What is the proper way to use <code>**kwargs</code> in Python when it comes to default values?

<code>kwargs</code> returns a dictionary, but what is the best way to set default values, or is there one?  Should I just access it as a dictionary?  Use get function?  

<code>class ExampleClass:
    def __init__(self, **kwargs):
        self.val = kwargs['val']
        self.val2 = kwargs.get('val2')
</code>

A simple question, but one that I can't find good resources on.  People do it different ways in code that I've seen and it's hard to know what to use.
"
1112343|"How do I capture SIGINT in Python?"|"I'm working on a python script that starts several processes and database connections. Every now and then I want to kill the script with a Ctrl+C signal, and I'd like to do some cleanup.

In Perl I'd do this:

<code>$SIG{'INT'} = 'exit_gracefully';

sub exit_gracefully {
    print ""Caught ^C \n"";
    exit (0);
}
</code>

How do I do the analogue of this in Python?
"
1155617|"Count occurrence of a character in a string"|"What's the simplest way to count the number of occurrences of a character in a string?

e.g. count the number of times <code>'a'</code> appears in <code>'Mary had a little lamb'</code>
"
1157106|"Remove all occurrences of a value from a list?"|"In Python <code>remove()</code> will remove the first occurrence of value in a list.

How to remove all occurrences of a value from a list, without sorting the list?

This is what I have in mind.

<code>&gt;&gt;&gt; x = [1, 2, 3, 4, 2, 2, 3]
&gt;&gt;&gt; def remove_values_from_list(the_list, val):
        while val in the_list:
            the_list.remove(val)
&gt;&gt;&gt; remove_values_from_list(x, 2)
&gt;&gt;&gt; x
[1, 3, 4, 3]
</code>
"
1185524|"How to trim whitespace (including tabs)?"|"Is there a function that will trim not only spaces for whitespace, but also tabs?
"
1186789|"What is the best way to call a Python script from another Python script?"|"I have a script named test1.py which is not in a module. It just has code that should execute when the script itself is run. There are no functions, classes, methods, etc. I have another script which runs as a service. I want to call test1.py from the script running as a service.

For example:

File test1.py

<code>print ""I am a test""
print ""see! I do nothing productive.""
</code>

File service.py

<code># Lots of stuff here
test1.py # do whatever is in test1.py
</code>

I'm aware of one method which is opening the file, reading the contents, and basically eval'ing it. I'm assuming there's a better way of doing this. Or at least I hope so.
"
1187970|"How to exit from Python without traceback?"|"I would like to know how to I exit from Python without having an traceback dump on the output. 

I still want want to be able to return an error code but I do not want to display the traceback log.

I want to be able to exit using <code>exit(number)</code> without trace but in case of an Exception (not an exit) I want the trace.
"
1196074|"How to start a background process in Python?"|"I'm trying to port a shell script to the much more readable python version. The original shell script starts several processes (utilities, monitors, etc.) in the background with ""&amp;"". How can I achieve the same effect in python? I'd like these processes not to die when the python scripts complete. I am sure it's related to the concept of a daemon somehow, but I couldn't find how to do this easily.
"
1207406|"Remove items from a list while iterating"|"I'm iterating over a list of tuples in Python, and am attempting to remove them if they meet certain criteria. 

<code>for tup in somelist:
    if determine(tup):
         code_to_remove_tup
</code>

What should I use in place of <code>code_to_remove_tup</code>? I can't figure out how to remove the item in this fashion.
"
1207457|"Convert a Unicode string to a string in Python (containing extra symbols)"|"How do you convert a Unicode string (containing extra characters like £ $, etc.) into a Python string?
"
1228299|"Change one character in a string?"|"What is the easiest way in Python to replace a character in a string like: 

<code>text = ""abcdefg"";
text[1] = ""Z"";
           ^
</code>
"
1231688|"How do I remove packages installed with Python's easy_install?"|"Python's <code>easy_install</code> makes installing new packages extremely convenient. However, as far as I can tell, it doesn't implement the other common features of a dependency manager - listing and removing installed packages.

What is the best way of finding out what's installed, and what is the preferred way of removing installed packages? Are there any files that need to be updated if I remove packages manually (e.g. by <code>rm /usr/local/lib/python2.6/dist-packages/my_installed_pkg.egg</code> or similar)?
"
1250103|"AttributeError: 'module' object has no attribute"|"I have two python modules:

a.py

<code>import b

def hello():
  print ""hello""

print ""a.py""
print hello()
print b.hi()
</code>

b.py

<code>import a

def hi():
  print ""hi""
</code>

When I run <code>a.py</code>, I get:

<code>AttributeError: 'module' object has no attribute 'hi'
</code>

What does the error mean?  How do I fix it?
"
1260792|"Import a file from a subdirectory?"|"I have a file called <code>tester.py</code>, located on <code>/project</code>.

<code>/project</code> has a subdirectory called <code>lib</code>, with a file called <code>BoxTime.py</code>:

<code>/project/tester.py
/project/lib/BoxTime.py
</code>

I want to import <code>BoxTime</code> from <code>tester</code>. I have tried this:

<code>import lib.BoxTime
</code>

Which resulted:

<code>Traceback (most recent call last):
  File ""./tester.py"", line 3, in &lt;module&gt;
    import lib.BoxTime
ImportError: No module named lib.BoxTime
</code>

Any ideas how to import <code>BoxTime</code> from the subdirectory?

EDIT

The <code>__init__.py</code> was the problem, but don't forget to refer to <code>BoxTime</code> as <code>lib.BoxTime</code>, or use:

<code>import lib.BoxTime as BT
...
BT.bt_function()
</code>
"
1265665|"Python: Check if a string represents an int, Without using Try/Except?"|"Is there any way to tell whether a string represents an integer (e.g., <code>'3'</code>, <code>'-17'</code> but not <code>'3.14'</code> or <code>'asfasfas'</code>) Without using a try/except mechanism?

<code>is_int('3.14') = False
is_int('-7')   = True
</code>
"
1267869|"How can I force division to be floating point? Division keeps rounding down to 0"|"I have two integer values <code>a</code> and <code>b</code>, but I need their ratio in floating point.  I know that <code>a&lt;b</code> and I want to calculate <code>a/b</code>, so if I use integer division I'll always get 0 with a remainder of <code>a</code>.

How can I force <code>c</code> to be a floating point number in Python in the following?

<code>c = a / b
</code>
"
1301346|"What is the meaning of a single- and a double-underscore before an object name?"|"I want to clear this up once and for all. Can someone please explain the exact meaning of having leading underscores before an object's name in Python? Also explain the difference between a single and a double leading underscore. Also, does that meaning stay the same whether the object in question is a variable, a function, a method, etc?
"
1319615|"Proper way to declare custom exceptions in modern Python?"|"What's the proper way to declare custom exception classes in modern Python? My primary goal is to follow whatever standard other exception classes have, so that (for instance) any extra string I include in the exception is printed out by whatever tool caught the exception.

By ""modern Python"" I mean something that will run in Python 2.5 but be 'correct' for the Python 2.6 and Python 3.* way of doing things. And by ""custom"" I mean an Exception object that can include extra data about the cause of the error: a string, maybe also some other arbitrary object relevant to the exception.

I was tripped up by the following deprecation warning in Python 2.6.2:

<code>&gt;&gt;&gt; class MyError(Exception):
...     def __init__(self, message):
...         self.message = message
... 
&gt;&gt;&gt; MyError(""foo"")
_sandbox.py:3: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6
</code>

It seems crazy that <code>BaseException</code> has a special meaning for attributes named <code>message</code>. I gather from PEP-352 that attribute did have a special meaning in 2.5 they're trying to deprecate away, so I guess that name (and that one alone) is now forbidden? Ugh.

I'm also fuzzily aware that <code>Exception</code> has some magic parameter <code>args</code>, but I've never known how to use it. Nor am I sure it's the right way to do things going forward; a lot of the discussion I found online suggested they were trying to do away with args in Python 3.

Update: two answers have suggested overriding <code>__init__</code>, and <code>__str__</code>/<code>__unicode__</code>/<code>__repr__</code>. That seems like a lot of typing, is it necessary?
"
1323410|"'has_key()' or 'in'?"|"I wonder what is better to do:

<code>d = {'a': 1, 'b': 2}
'a' in d
True
</code>

or:

<code>d = {'a': 1, 'b': 2}
d.has_key('a')
True
</code>
"
1380860|"Add Variables to Tuple"|"I am learning Python and creating a database connection.
While trying to add to the DB, I am thinking of creating tuples out of information and then add them to the DB. 

What I am Doing:
I am taking information from the user and store it in variables. 
Can I add these variables into a tuple?  Can you please help me with the syntax?

Also if there is an efficient way of doing this, please share...

EDIT
Let me edit this question a bit...I only need the tuple to enter info into the DB.  Once the information is added to the DB, should I delete the tuple?  I mean I don't need the tuple anymore.
"
1388818|"How can I compare two lists in python and return matches"|"I want to take two lists and find the values that appear in both.

<code>a = [1, 2, 3, 4, 5]
b = [9, 8, 7, 6, 5]

returnMatches(a, b)
</code>

would return <code>[5]</code>, for instance.
"
1400608|"How to empty a list in Python?"|"It seems so ""dirty"" emptying a list in this way:

<code>while len(alist) &gt; 0 : alist.pop()
</code>

Does a clear way exist to do that?
"
1401712|"How can the euclidean distance be calculated with numpy?"|"I have two points in 3D:

<code>(xa, ya, za)
(xb, yb, zb)
</code>

And I want to calculate the distance:

<code>dist = sqrt((xa-xb)^2 + (ya-yb)^2 + (za-zb)^2)
</code>

What's the best way to do this with Numpy, or with Python in general?  I have:

<code>a = numpy.array((xa ,ya, za))
b = numpy.array((xb, yb, zb))
</code>
"
1432480|"Any way to clear python's IDLE window?"|"I know there's a similar topic about python console, but I do not know if they are the same. I tried system(""clear"") and it didn't work here.

How do I clear python's IDLE window?
"
1436703|"Difference between __str__ and __repr__ in Python"|"What is the difference between <code>__str__</code> and <code>__repr__</code> in <code>Python</code>?
"
1449494|"How do I install Python packages on Windows?"|"I'm having a hard time setting up python packages. EasyInstall from SetupTools is supposed to help that, but they don't have an executable for Python 2.6.

For instance to install Mechanize, I'm just supposed to put the Mechanize folder in C:\Python24\Lib\site-packages according to INSTALL.txt, but runnning the tests does not work. Can someone help shed some light on this? Thanks!
"
1450393|"How do you read from stdin in Python?"|"I'm trying to do some of the code golf challenges, but they all require the input to be taken from <code>stdin</code>. How do I get that in Python?
"
1471994|"What is setup.py?"|"Can anyone please explain, what is <code>setup.py</code> and how can it be configured or used?
"
1483429|"How to print an error in Python?"|"<code>try:
    something here
except:
    print 'the whatever error occurred.'
</code>

How can I print the error in my <code>except:</code> block?
"
1485841|"Behaviour of increment and decrement operators in Python"|"I notice that a pre-increment/decrement operator can be applied on a variable (like <code>++count</code>). It compiles, but it does not actually change the value of the variable!

What is the behavior of the pre-increment/decrement operators (++/--) in Python? 

Why does Python deviate from the behavior of these operators seen in C/C++?
"
1504717|"Why does comparing strings in Python using either '==' or 'is' sometimes produce a different result?"|"I've got a Python program where two variables are set to the value <code>'public'</code>. In a conditional expression I have the comparison <code>var1 is var2</code> which fails, but if I change it to <code>var1 == var2</code> it returns <code>True</code>.

Now if I open my Python interpreter and do the same ""is"" comparison, it succeeds.

<code>&gt;&gt;&gt; s1 = 'public'
&gt;&gt;&gt; s2 = 'public'
&gt;&gt;&gt; s2 is s1
True
</code>

What am I missing here?
"
1514553|"How to declare an array in Python?"|"How do I declare an array in Python?

I can't find any reference to arrays in the documentation. 
"
1522564|"How do I run a Python program?"|"So I'm starting like Python a bit, but I'm having trouble erm...running it. Lol

I'm using IDLE for now, but its no use whatsoever because you can only run a couple of lines at a time.

I'm also using Komodo Edit to create the actual .py files.

My question is, how can I run the .py files to test out the actual program? 

I'm using Windows 7, and Komodo Edit 5 as my IDE. Pressing F5 in Komodo doesn't do anythin at all.


"
1523427|"What is the common header format of Python files?"|"I came across the following header format for Python source files in a document about Python coding guidelines:

<code>#!/usr/bin/env python

""""""Foobar.py: Description of what foobar does.""""""

__author__      = ""Barack Obama""
__copyright__   = ""Copyright 2009, Planet Earth""
</code>

Is this the standard format of headers in the Python world?
What other fields/information can I put in the header?
Python gurus share your guidelines for good Python source headers :-)
"
1534210|"Use different Python version with virtualenv"|"I have a Debian system currently running with python 2.5.4. I got virtualenv properly installed, everything is working fine. Is there a possibility that I can use a virtualenv with a different version of Python?

I compiled Python 2.6.2 and would like to use it with some virtualenv. Is it enough to overwrite the binary file? Or do I have to change something in respect to the libraries?
"
1535327|"How to print a class or objects of class using print()?"|"I am learning the ropes in Python. When I try to print an object of class <code>Foobar</code> using the <code>print()</code> function, I get an output like this:

<code>&lt;__main__.Foobar instance at 0x7ff2a18c&gt;
</code>

Is there a way I can set the printing behaviour (or the string representation) of a class and its objects? For instance, when I call <code>print()</code> on a class object, I would like to print its data members in a certain format. How to achieve this in Python?

If you are familiar with C++ classes, the above can be achieved for the standard <code>ostream</code> by adding a <code>friend ostream&amp; operator &lt;&lt; (ostream&amp;, const Foobar&amp;)</code> method for the class.
"
1540049|"Replace values in list using Python"|"I have a list where I want to replace values with None where condition() returns True.

<code>[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
</code>

For example, if condition checks bool(item%2) should return:

<code>[None, 1, None, 3, None, 5, None, 7, None, 9, None]
</code>

What is the most efficient way to do this?
"
1549641|"How to capitalize the first letter of each word in a string (Python)?"|"<code>s = 'the brown fox'
</code>

...do something here...

<code>s</code> should be :

<code>'The Brown Fox'
</code>

What's the easiest way to do this?
"
1549801|"Differences between isinstance() and type() in python"|"What are the differences between these two code fragments? Which way is considered to be more pythonic?

Using <code>type()</code>:

<code>import types

if type(a) is types.DictType:
    do_something()
if type(b) in types.StringTypes:
    do_something_else()
</code>

Using <code>isinstance()</code>:

<code>if isinstance(a, dict):
    do_something()
if isinstance(b, str) or isinstance(b, unicode):
    do_something_else()
</code>

Edit: This seems to be discussed already: link.
"
1550226|"python setup.py uninstall"|"I have installed a python package with <code>python setup.py install</code>.

How do I uninstall it?
"
1557571|"How do I get time of a Python program's execution?"|"I have a command line program in Python that takes a while to finish. I want to know the exact time it takes to finish running.

I've looked at the <code>timeit</code> module, but it seems it's only for small snippets of code. I want to time the whole program.
"
1592565|"Determine if variable is defined in Python"|"
  Possible Duplicate:
  Easy way to check that variable is defined in python?
  How do I check if a variable exists in Python?  




How do you know whether a variable has been set at a particular place in the code at runtime? This is not always obvious because (1) the variable could be conditionally set, and (2) the variable could be conditionally deleted. I'm looking for something like <code>defined()</code> in Perl or <code>isset()</code> in PHP or <code>defined?</code> in Ruby.

<code>if condition:
    a = 42

# is ""a"" defined here?

if other_condition:
    del a

# is ""a"" defined here?
</code>
"
1602934|"Check if a given key already exists in a dictionary"|"I wanted to test if a key exists in a dictionary before updating the value for the key.
I wrote the following code:

<code>if 'key1' in dict.keys():
  print ""blah""
else:
  print ""boo""
</code>

I think this is not the best way to accomplish this task. Is there a better way to test for a key in the dictionary?
"
1614236|"In Python, how do I convert all of the items in a list to floats?"|"I have a script which reads a text file, pulls decimal numbers out of it as strings and places them into a list.

So I have this list: <code>['0.49', '0.54', '0.54', '0.54', '0.54', '0.54', '0.55', '0.54', '0.54', '0.54', '0.55', '0.55', '0.55', '0.54', '0.55', '0.55', '0.54', '0.55', '0.55', '0.54']</code>

How do I convert each of the values in the list from a string to a float?

I have tried:

<code>for item in list:
    float(item)
</code>

But this doesn't seem to work for me.
"
1623039|"Python debugging tips"|"What are your best tips for debugging Python?

Please don't just list a particular debugger without saying what it can actually do.

Related


What are good ways to make my Python code run first time? - This discusses minimizing errors

"
1641219|"Does Python have “private” variables in classes?"|"I'm coming from the Java world and reading Bruce Eckels' Python 3 Patterns, Recipes and Idioms. 

While reading about classes, it goes on to say that in Python there is no need to declare instance variables. You just use them in the constructor, and boom, they are there. 

So for example:

<code>class Simple:
    def __init__(self1, str):
        print(""inside the simple constructor"")
        self1.s = str
    def show(self1):
        print(self1.s)
    def showMsg (self, msg):
        print (msg + ':', self.show())
</code>

If that’s true, then any object of class <code>Simple</code> can just change the value of variable <code>s</code> outside of the class. 

For example: 

<code>if __name__ == ""__main__"":
    x = Simple(""constructor argument"")
    x.s = ""test15"" # this changes the value
    x.show()
    x.showMsg(""A message"")
</code>

In Java, we have been taught about public/private/protected variables.  Those keywords make sense because at times you want variables in a class to which no one outside the class has access to. 

Why is that not required in Python?
"
1663807|"How can I iterate through two lists in parallel?"|"I have two iterables in Python, and I want to go over them in pairs:

<code>foo = (1, 2, 3)
bar = (4, 5, 6)

for (f, b) in some_iterator(foo, bar):
    print ""f: "", f, ""; b: "", b
</code>

It should result in:

<code>f: 1; b: 4
f: 2; b: 5
f: 3; b: 6
</code>

One way to do it is to iterate over the indices:

<code>for i in xrange(len(foo)):
    print ""f: "", foo[i], ""; b: "", b[i]
</code>

But that seems somewhat unpythonic to me. Is there a better way to do it?
"
1679384|"Converting Python Dictionary to List"|"
  Possible Duplicate:
  How can I convert a Python dictionary to a list of tuples?  




I'm trying to convert a Python dictionary into a Python list, in order to perform some calculations.

<code>#My dictionary
dict = {}
dict['Capital']=""London""
dict['Food']=""Fish&amp;Chips""
dict['2012']=""Olympics""

#lists
temp = []
dictList = []

#My attempt:
for key, value in dict.iteritems():
    aKey = key
    aValue = value
    temp.append(aKey)
    temp.append(aValue)
    dictList.append(temp) 
    aKey = """"
    aValue = """"
</code>

That's my attempt at it... but I can't work out what's wrong?
"
1702586|"How to Execute a Python File in Notepad ++?"|"I prefer using Notepad ++ for developing,

How do I execute the files in Python through Notepad++?
"
1712227|"How to get the size of a list"|"<code>items = []
items.append(""apple"")
items.append(""orange"")
items.append(""banana"")

# FAKE METHOD::
items.amount()  # Should return 3
</code>

How do I get the number of elements in the list?
"
1720421|"How to append list to second list (concatenate lists)"|"How do I concatenate two lists in Python?

Example:

<code>listone = [1, 2, 3]
listtwo = [4, 5, 6]
</code>

Expected outcome:

<code>joinedlist == [1, 2, 3, 4, 5, 6]
</code>
"
1747817|"Create a dictionary with list comprehension in Python"|"I like the Python list comprehension syntax.

Can it be used to create dictionaries too? For example, by iterating over pairs of keys and values:

<code>mydict = {(k,v) for (k,v) in blah blah blah}  # doesn't work
</code>
"
1748641|"Boolean in Python"|"Does Python actually contain a Boolean value? I know that you can do:

<code>checker = 1
if checker:
    #dostuff
</code>

But I'm quite pedantic and enjoy seeing booleans in Java. For instance:

<code>Boolean checker;
if (someDecision)
{
    checker = true;
}
if(checker)
{
    //some stuff
}
</code>

Is there such a thing as this in Python? I can't seem to find anything like it in the documentation.
"
1769403|"Understanding kwargs in Python"|"What are the uses for <code>**kwargs</code> in Python?

I know you can do an <code>objects.filter</code> on a table and pass in a <code>**kwargs</code> argument. &nbsp;

Can I also do this for specifying time deltas i.e. <code>timedelta(hours = time1)</code>? 

How exactly does it work? Is it classes as 'unpacking'? Like <code>a,b=1,2</code>?
"
1798796|"python : list index out of range error"|"I have written a simple python program 

<code>l=[1,2,3,0,0,1]
for i in range(0,len(l)):
       if l[i]==0:
           l.pop(i)
</code>

This gives me error 'list index out of range' on line <code>if l[i]==0:</code>

After debugging I could figure out that <code>i</code> is getting incremented and list is getting reduced.
However, I have loop termination condition <code>i &lt; len(l)</code>. Then why I am getting such error? 
"
1810743|"How to set the current working directory in Python?"|"How to set the current working directory in Python?
"
1835018|"How to check if an object is a list or tuple (but not string)?"|"This is what I normally do in order to ascertain that the input is a <code>list</code>/<code>tuple</code> - but not a <code>str</code>. Because many times I stumbled upon bugs where a function passes a <code>str</code> object by mistake, and the target function does <code>for x in lst</code> assuming that <code>lst</code> is actually a <code>list</code> or <code>tuple</code>.

<code>assert isinstance(lst, (list, tuple))
</code>

My question is: is there a better way of achieving this?
"
1841565|"ValueError: invalid literal for int() with base 10: ''"|"I am creating a program that reads a file and if the first line of the file is not blank, it reads the next four lines.  Calculations are performed on those lines and then the next line is read.  If that line is not empty it continues.  However, I am getting this error:

<code>ValueError: invalid literal for int() with base 10: ''.` 
</code>

It is reading the first line but can't convert it to an integer.  

What can I do to fix this problem?

The Code:

<code>file_to_read = raw_input(""Enter file name of tests (empty string to end program):"")
try:
    infile = open(file_to_read, 'r')
    while file_to_read != "" "":
        file_to_write = raw_input(""Enter output file name (.csv will be appended to it):"")
        file_to_write = file_to_write + "".csv""
        outfile = open(file_to_write, ""w"")
        readings = (infile.readline())
        print readings
        while readings != 0:
            global count
            readings = int(readings)
            minimum = (infile.readline())
            maximum = (infile.readline())
</code>
"
1876191|"Explain Python .join()"|"I'm pretty new to Python and am completely confused by <code>.join()</code> which I have read is the preferred method for concatenating strings.

I try:

<code>strid = repr(595)
print array.array('c', random.sample(string.ascii_letters, 20 - len(strid)))
    .tostring().join(strid)
</code>

and get something like:

<code>5wlfgALGbXOahekxSs9wlfgALGbXOahekxSs5
</code>

Why does it work like this?  Shouldn't the <code>595</code> just be automatically appended?
"
1912434|"How do I parse XML in Python?"|"I have many rows in a database that contains xml and I'm trying to write a Python script that will go through those rows and count how many instances of a particular node attribute show up. For instance, my tree looks like:

<code>&lt;foo&gt;
   &lt;bar&gt;
      &lt;type foobar=""1""/&gt;
      &lt;type foobar=""2""/&gt;
   &lt;/bar&gt;
&lt;/foo&gt;
</code>

How can I access the attributes 1 and 2 in the XML using Python?
"
1934675|"How to execute Python scripts in Windows?"|"I have a simple script blah.py (using Python 2):

<code>import sys
print sys.argv[1]
</code>

If I execute my script by:

<code>python c:/..../blah.py argument
</code>

It prints argument but if I execute script by:

<code>blah.py argument
</code>

error occurs:


  IndexError...


So arguments do not pass to script.

python.exe in PATH. Folder with blah.py also in PATH.
python.exe is default program to execute *.py files.

What is the problem?
"
1945920|"Why doesn't os.path.join() work in this case?"|"The below code will not join, when debugged the command does not store the whole path but just the last entry.

<code>os.path.join('/home/build/test/sandboxes/', todaystr, '/new_sandbox/')
</code>

When I test this it only stores the <code>/new_sandbox/</code> part of the code.
"
1952464|"In Python, how do I determine if an object is iterable?"|"Is there a method like <code>isiterable</code>? The only solution I have found so far is to call

<code>hasattr(myObj, '__iter__')
</code>

But I am not sure how fool-proof this is.
"
1995615|"How can I format a decimal to always show 2 decimal places?"|"I want to display:

<code>49</code> as <code>49.00</code>

and:

<code>54.9</code> as <code>54.90</code>

Regardless of the length of the decimal or whether there are are any decimal places, I would like to display a <code>Decimal</code> with 2 decimal places, and I'd like to do it in an efficient way. The purpose is to display money values.

eg, <code>4898489.00</code>
"
2020598|"In Python how should I test if a variable is None, True or False"|"I have a function that can return one of three things:


success (<code>True</code>)
failure (<code>False</code>)
error reading/parsing stream (<code>None</code>)


My question is, if I'm not supposed to test against <code>True</code> or <code>False</code>, how should I see what the result is. Below is how I'm currently doing it:

<code>result = simulate(open(""myfile""))
if result == None:
    print ""error parsing stream""
elif result == True: # shouldn't do this
    print ""result pass""
else:
    print ""result fail""
</code>

is it really as simple as removing the <code>== True</code> part or should I add a tri-bool data-type. I do not want the <code>simulate</code> function to throw an exception as all I want the outer program to do with an error is log it and continue. 
"
2052390|"Manually raising (throwing) an exception in Python"|"How can I raise an exception in Python so that it can later be caught via an <code>except</code> block?
"
2081836|"Reading specific lines only (Python)"|"I'm using a for loop to read a file, but I only want to read specific lines, say line #26 and #30. Is there any built-in feature to achieve this?

Thanks
"
2084069|"Create a .csv file with values from a Python list"|"I am trying to create a .csv file with the values from a Python list. When I print the values in the list they are all unicode (?), i.e. they look something like this 

<code>[u'value 1', u'value 2', ...]
</code>

If I iterate through the values in the list i.e. <code>for v in mylist: print v</code> they appear to be plain text.

And I can put a <code>,</code> between each with <code>print ','.join(mylist)</code>

And I can output to a file, i.e. 

<code>myfile = open(...)
print &gt;&gt;myfile, ','.join(mylist)
</code>

But I want to output to a CSV and have delimiters around the values in the list e.g.

<code>""value 1"", ""value 2"", ... 
</code>

I can't find an easy way to include the delimiters in the formatting, e.g. I have tried through the <code>join</code> statement. How can I do this?
"
2104080|"How to check file size in python?"|"I am writing a Python script in Windows. I want to do something based on the file size. For example, if the size is greater than 0, I will send an email to somebody, otherwise continue to other things. 

How do I check the file size?
"
2186525|"Use a Glob() to find files recursively in Python?"|"This is what I have:

<code>glob(os.path.join('src','*.c'))
</code>

but I want to search the subfolders of src. Something like this would work:

<code>glob(os.path.join('src','*.c'))
glob(os.path.join('src','*','*.c'))
glob(os.path.join('src','*','*','*.c'))
glob(os.path.join('src','*','*','*','*.c'))
</code>

But this is obviously limited and clunky.
"
2213551|"Installing SciPy with pip"|"It is possible to install NumPy with pip using <code>pip install numpy</code>. 

Is there a similar possibility with SciPy? (Doing <code>pip install scipy</code> does not work.)



Update

The package SciPy is now available to be installed with <code>pip</code>!
"
2225038|"Determine the type of an object?"|"Is there a simple way to determine if a variable is a list, dictionary, or something else? I am getting an object back that may be either type and I need to be able to tell the difference.
"
2257441|"Random string generation with upper case letters and digits in Python"|"I want to generate a string of size N.

It should be made up of numbers and uppercase English letters such as:


6U1S75
4Z4UKK
U911K4


How can I achieve this in a pythonic way?
"
2259382|"Pythonic way to check if a file exists?"|"Which is the preferred way to check if a file exists and if not create it?
"
2269827|"How to convert an int to a hex string?"|"I want to take an integer (that will be &lt;= 255), to a hex string representation

e.g.: I want to pass in <code>65</code> and get out <code>'\x41'</code>, or <code>255</code> and get <code>'\xff'</code>.

I've tried doing this with the <code>struct.pack('c',</code>65<code>)</code>, but that chokes on anything above <code>9</code> since it wants to take in a single character string.
"
2294493|"How to get the position of a character in Python?"|"How can I get the position of a character inside a string in python?
"
2325923|"How to fix ""ImportError: No module named ..."" error in Python?"|"What is the correct way to fix this ImportError error?

I have the following directory structure:

<code>/home/bodacydo
/home/bodacydo/work
/home/bodacydo/work/project
/home/bodacydo/work/project/programs
/home/bodacydo/work/project/foo
</code>

And I am in the directory

<code>/home/bodacydo/work/project
</code>

Now if I type

<code>python ./programs/my_python_program.py
</code>

I instantly get

<code>ImportError: No module named foo.tasks
</code>

The <code>./programs/my_python_program.py</code> contains the following line:

<code>from foo.tasks import my_function
</code>

I can't understand why python won't find <code>./foo/tasks.py</code> - it's there.

If I do it from the Python shell, then it works:

<code>python
&gt;&gt;&gt; from foo.tasks import my_function
</code>

It only doesn't work if I call it via <code>python ./programs/my_python_program.py</code> script.
"
2349991|"Python: How to import other Python files"|"How do I import other files in Python?


How exactly can I import a specific python file like <code>import file.py</code>?
How can I import a folder instead of a specific file?
I want to load a Python file dynamically at runtime, based on user
input.
I want to know how to load just one specific part from the file.


For example, in <code>main.py</code> I have:

<code>from extra import * 
</code>

although this gives me all the definitions in <code>extra.py</code> when maybe all I want is a single definition:

<code>def gap():
    print
    print
</code>

What do I add to the <code>import</code> statement to just get <code>gap</code> from <code>extra.py</code>?
"
2356501|"How do you round UP a number in Python?"|"This problem is killing me. How does one roundup a number UP in Python?

I tried round(number) but it round the number down. Example:

<code>round(2.3) = 2.0 and not 3, what I would like
</code>

The I tried int(number + .5) but it round the number down again! Example:

<code>int(2.3 + .5) = 2
</code>

Then I tried round(number + .5) but it won't work in edge cases. Example:

<code>WAIT! THIS WORKED!
</code>

Please advise.
"
2365411|"Python: Convert Unicode to ASCII without errors"|"My code just scrapes a web page, then converts it to Unicode.

<code>html = urllib.urlopen(link).read()
html.encode(""utf8"",""ignore"")
self.response.out.write(html)
</code>

But I get a <code>UnicodeDecodeError</code>:



<code>Traceback (most recent call last):
  File ""/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/__init__.py"", line 507, in __call__
    handler.get(*groups)
  File ""/Users/greg/clounce/main.py"", line 55, in get
    html.encode(""utf8"",""ignore"")
UnicodeDecodeError: 'ascii' codec can't decode byte 0xa0 in position 2818: ordinal not in range(128)
</code>

So I assume that means the HTML contains some wrongly-formed attempt at Unicode somewhere. Can I just drop whatever code bytes are causing the problem instead of getting an error?
"
2395160|"What is the correct syntax for 'else if'?"|"I'm a new Python programmer who is making the leap from 2.6.4 to 3.1.1. Everything has gone fine until I tried to use the 'else if' statement. The interpreter gives me a syntax error after the 'if' in 'else if' for a reason I can't seem to figure out.

<code>def function(a):
    if a == '1':
        print ('1a')
    else if a == '2'
        print ('2a')
    else print ('3a')

function(input('input:'))
</code>

I'm probably missing something very simple; however, I haven't been able to find the answer on my own. 
"
2397141|"How to initialize a two-dimensional array in Python?"|"I'm beginning python and I'm trying to use a two-dimensional list, that I initially fill up with the same variable in every place. I came up with this:

<code>def initialize_twodlist(foo):
    twod_list = []
    new = []
    for i in range (0, 10):
        for j in range (0, 10):
            new.append(foo)
        twod_list.append(new)
        new = []
</code>

It gives the desired result, but feels like a workaround. Is there an easier/shorter/more elegant way to do this?
"
2428092|"Creating a JSON response using Django and Python"|"I'm trying to convert a server side Ajax response script into a Django HttpResponse, but apparently it's not working.

This is the server-side script:

<code>/* RECEIVE VALUE */
$validateValue=$_POST['validateValue'];
$validateId=$_POST['validateId'];
$validateError=$_POST['validateError'];

/* RETURN VALUE */
$arrayToJs = array();
$arrayToJs[0] = $validateId;
$arrayToJs[1] = $validateError;

if($validateValue ==""Testuser""){  // Validate??
    $arrayToJs[2] = ""true"";       // RETURN TRUE
    echo '{""jsonValidateReturn"":'.json_encode($arrayToJs).'}';  // RETURN ARRAY WITH success
}
else{
    for($x=0;$x&lt;1000000;$x++){
        if($x == 990000){
            $arrayToJs[2] = ""false"";
            echo '{""jsonValidateReturn"":'.json_encode($arrayToJs).'}';   // RETURNS ARRAY WITH ERROR.
        }
    }
}
</code>

And this is the converted code

<code>def validate_user(request):
    if request.method == 'POST':
        vld_value = request.POST.get('validateValue')
        vld_id = request.POST.get('validateId')
        vld_error = request.POST.get('validateError')

        array_to_js = [vld_id, vld_error, False]

        if vld_value == ""TestUser"":
            array_to_js[2] = True
            x = simplejson.dumps(array_to_js)
            return HttpResponse(x)
        else:
            array_to_js[2] = False
            x = simplejson.dumps(array_to_js)
            error = 'Error'
            return render_to_response('index.html',{'error':error},context_instance=RequestContext(request))
    return render_to_response('index.html',context_instance=RequestContext(request))
</code>

I'm using simplejson to encode the Python list (so it will return a JSON array). I couldn't figure out the problem yet. But I think that I did something wrong about the 'echo'.
"
2429511|"Why do people write #!/usr/bin/env python on the first line of a Python script?"|"It seems to me like the files run the same without that line.
"
2465921|"How to copy a dictionary and only edit the copy"|"Can someone please explain this to me? This doesn't make any sense to me.

I copy a dictionary into another and edit the second and both are changed. Why is this happening?

<code>&gt;&gt;&gt; dict1 = {""key1"": ""value1"", ""key2"": ""value2""}
&gt;&gt;&gt; dict2 = dict1
&gt;&gt;&gt; dict2
{'key2': 'value2', 'key1': 'value1'}
&gt;&gt;&gt; dict2[""key2""] = ""WHY?!""
&gt;&gt;&gt; dict1
{'key2': 'WHY?!', 'key1': 'value1'}
</code>
"
2474015|"Getting the index of the returned max or min item using max()/min() on a list"|"I'm using Python's <code>max</code> and <code>min</code> functions on lists for a minimax algorithm, and I need the index of the value returned by <code>max()</code> or <code>min()</code>. In other words, I need to know which move produced the max (at a first player's turn) or min (second player) value.

<code>for i in range(9):
    newBoard = currentBoard.newBoardWithMove([i / 3, i % 3], player)

    if newBoard:
        temp = minMax(newBoard, depth + 1, not isMinLevel)  
        values.append(temp)

if isMinLevel:
    return min(values)
else:
    return max(values)
</code>

I need to be able to return the actual index of the min or max value, not just the value.
"
2485466|"Python's equivalent of && (logical-and) in an if-statement"|"Here's my code:

<code># F. front_back
# Consider dividing a string into two halves.
# If the length is even, the front and back halves are the same length.
# If the length is odd, we'll say that the extra char goes in the front half.
# e.g. 'abcde', the front half is 'abc', the back half 'de'.
# Given 2 strings, a and b, return a string of the form
#  a-front + b-front + a-back + b-back
def front_back(a, b):
  # +++your code here+++
  if len(a) % 2 == 0 &amp;&amp; len(b) % 2 == 0:
    return a[:(len(a)/2)] + b[:(len(b)/2)] + a[(len(a)/2):] + b[(len(b)/2):] 
  else:
    #todo! Not yet done. :P
  return
</code>

I'm getting an error in the IF conditional. What am I doing wrong?
"
2502833|"Store output of subprocess.Popen call in a string"|"I'm trying to make a system call in Python and store the output to a string that I can manipulate in the Python program.

<code>#!/usr/bin/python
import subprocess
p2 = subprocess.Popen(""ntpq -p"")
</code>

I've tried a few things including some of the suggestions here:

Retrieving the output of subprocess.call()

but without any luck.
"
2504411|"Proper indentation for Python multiline strings"|"What is the proper indentation for Python multiline strings within a function?

<code>    def method():
        string = """"""line one
line two
line three""""""
</code>

or

<code>    def method():
        string = """"""line one
        line two
        line three""""""
</code>

or something else?

It looks kind of weird to have the string hanging outside the function in the first example.
"
2573135|"Python progression path - From apprentice to guru"|"I've been learning, working, and playing with Python for a year and a half now. As a biologist slowly making the turn to bio-informatics, this language has been at the very core of all the major contributions I have made in the lab. I more or less fell in love with the way Python permits me to express beautiful solutions and also with the semantics of the language that allows such a natural flow from thoughts to workable code.

What I would like to know is your answer to a kind of question I have seldom seen in this or other forums. This question seems central to me for anyone on the path to Python improvement but who wonders what his next steps should be.

Let me sum up what I do NOT want to ask first ;)


I don't want to know how to QUICKLY learn Python
Nor do I want to find out the best way to get acquainted with the language
Finally, I don't want to know a 'one trick that does it all' approach.


What I do want to know your opinion about, is:

What are the steps YOU would recommend to a Python journeyman, from apprenticeship to guru status (feel free to stop wherever your expertise dictates it), in order that one IMPROVES CONSTANTLY, becoming a better and better Python coder, one step at a time. Some of the people on SO almost seem worthy of worship for their Python prowess, please enlighten us :)

The kind of answers I would enjoy (but feel free to surprise the readership :P ), is formatted more or less like this:


Read this (eg: python tutorial), pay attention to that kind of details
Code for so manytime/problems/lines of code
Then, read this (eg: this or that book), but this time, pay attention to this
Tackle a few real-life problems
Then, proceed to reading Y.
Be sure to grasp these concepts
Code for X time
Come back to such and such basics or move further to...
(you get the point :)


I really care about knowing your opinion on what exactly one should pay attention to, at various stages, in order to progress CONSTANTLY (with due efforts, of course). If you come from a specific field of expertise, discuss the path you see as appropriate in this field.

EDIT: Thanks to your great input, I'm back on the Python improvement track! I really appreciate!
"
2582138|"finding and replacing elements in a list (python)"|"I have to search through a list and replace all occurrences of one element with another. So far my attempts in code are getting me nowhere, what is the best way to do this?

For example, suppose my list has the following integers

<code>&gt;&gt;&gt; a = [1,2,3,4,5,1,2,3,4,5,1]
</code>

and I need to replace all occurrences of the number 1 with the value 10 so the output I need is 

<code>&gt;&gt;&gt; a = [10, 2, 3, 4, 5, 10, 2, 3, 4, 5, 10]
</code>

Thus my goal is to replace all instances of the number 1 with the number 10.
"
2600191|"How can I count the occurrences of a list item in Python?"|"Given an item, how can I count its occurrences in a list in Python?
"
2612802|"How to clone or copy a list?"|"What are the options to clone or copy a list in Python?

Using <code>new_list = my_list</code> then modifies <code>new_list</code> every time <code>my_list</code> changes.
Why is this?
"
2632677|"Python integer incrementing with ++"|"
  Possible Duplicate:
  Python: Behaviour of increment and decrement operators  




I've always laughed to myself when I've looked back at my VB6 days and thought, ""What modern language doesn't allow incrementing with double plus signs?"":

<code>number++
</code>

To my surprise, I can't find anything about this in the Python docs. Must I really subject myself to <code>number = number + 1</code>? Don't people use the <code>++/--</code> notation?
"
2682745|"How do I create a constant in Python?"|"Is there a way to declare a constant in Python? In Java we can create constant values in this manner:

<code>public static final String CONST_NAME = ""Name"";
</code>

What is the equivalent of the above Java constant declaration in Python?
"
2709821|"What is the purpose of self?"|"What is the purpose of the <code>self</code> word in Python? I understand it refers to the specific object created from that class, but I can't see why it explicitly needs to be added to every function as a parameter. To illustrate, in Ruby I can do this:

<code>class myClass
    def myFunc(name)
        @name = name
    end
end
</code>

Which I understand, quite easily. However in Python I need to include <code>self</code>:

<code>class myClass:
    def myFunc(self, name):
        self.name = name
</code>

Can anyone talk me through this? It is not something I've come across in my (admittedly limited) experience.
"
2710940|"Python `if x is not None` or `if not x is None`?"|"I've always thought of the <code>if not x is None</code> version to be more clear, but Google's style guide and PEP-8 both use <code>if x is not None</code>. Is there any minor performance difference (I'm assuming not), and is there any case where one really doesn't fit (making the other a clear winner for my convention)?*

*I'm referring to any singleton, rather than just <code>None</code>.


  ...to compare singletons like
  None. Use is  or is not.

"
2711579|"Concatenate strings in python 2.4?"|"How to concatenate strings in python?  

For example:

<code>Section = 'C_type'
</code>

Concatenate it with <code>Sec_</code> to form the string:

<code>Sec_C_type
</code>
"
2720014|"Upgrading all packages with pip"|"Is it possible to upgrade all Python packages at one time with <code>pip</code>?

Note that there is a feature request for this on the official issue tracker.
"
2759067|"Rename multiple files in a directory in Python"|"I'm trying to rename some files in a directory using Python.

Say I have a file called <code>CHEESE_CHEESE_TYPE.***</code> and want to remove <code>CHEESE_</code> so my resulting filename would be <code>CHEESE_TYPE</code>

I'm trying to use the <code>os.path.split</code> but it's not working properly. I have also considered using string manipulations, but have not been successful with that either.
"
2775864|"Python Create unix timestamp five minutes in the future"|"I have to create an ""Expires"" value 5 minutes in the future, but I have to supply it in UNIX Timestamp format.  I have this so far, but it seems like a hack.

<code>def expires():
    '''return a UNIX style timestamp representing 5 minutes from now'''
    epoch = datetime.datetime(1970, 1, 1)
    seconds_in_a_day = 60 * 60 * 24
    five_minutes = datetime.timedelta(seconds=5*60)
    five_minutes_from_now = datetime.datetime.now() + five_minutes
    since_epoch = five_minutes_from_now - epoch
    return since_epoch.days * seconds_in_a_day + since_epoch.seconds
</code>

Is there a module or function that does the timestamp conversion for me?
"
2792650|"Python3 error: ""Import error: No module name urllib2"""|"Here's my code:

<code>import urllib2.request

response = urllib2.urlopen(""http://www.google.com"")
html = response.read()
print(html)
</code>

Any help?
"
2793324|"Is there a simple way to delete a list element by value?"|"<code>a=[1,2,3,4]
b=a.index(6)
del a[b]
print a
</code>

The above shows the following error:

<code>Traceback (most recent call last):
  File ""D:\zjm_code\a.py"", line 6, in &lt;module&gt;
    b=a.index(6)
ValueError: list.index(x): x not in list
</code>

So I have to do this:

<code>a=[1,2,3,4]
try:
    b=a.index(6)
    del a[b]
except:
    pass
print a
</code>

But is there not a simpler way to do this?
"
2802726|"Putting a simple if-then statement on one line"|"
  Possible Duplicate:
  Python Ternary Operator  




I'm just getting into Python and I really like the terseness of the syntax. However, is there an easier way of writing an if-then statement so it fits on one line?

For example:

<code>if count == N:
    count = 0
else:
    count = N + 1
</code>

Is there a simpler way of writing this? I mean, in Objective-C I would write this as:

<code>count = count == N ? 0 : count + 1;
</code>

Is there something similar for Python?

Update

I know that in this instance I can use <code>count == (count + 1) % N</code>. 

I'm asking about the general syntax.
"
2817869|"error: Unable to find vcvarsall.bat"|"I tried to install the Python package dulwich:

<code>pip install dulwich
</code>

But I get a cryptic error message:

<code>error: Unable to find vcvarsall.bat
</code>

The same happens if I try installing the package manually:

<code>&gt; python setup.py install
running build_ext
building 'dulwich._objects' extension
error: Unable to find vcvarsall.bat
</code>
"
2835559|"Parsing values from a JSON file?"|"I have this JSON in a file:

<code>{
    ""maps"": [
        {
            ""id"": ""blabla"",
            ""iscategorical"": ""0""
        },
        {
            ""id"": ""blabla"",
            ""iscategorical"": ""0""
        }
    ],
    ""masks"": [
        ""id"": ""valore""
    ],
    ""om_points"": ""value"",
    ""parameters"": [
        ""id"": ""valore""
    ]
}
</code>

I wrote this script which prints all of the json text:

<code>json_data=open(file_directory).read()

data = json.loads(json_data)
pprint(data)
</code>

How can I parse the file and extract single values?
"
2846653|"How to use threading in Python?"|"I am trying to understand threading in Python. I've looked at the documentation and examples, but quite frankly, many examples are overly sophisticated and I'm having trouble understanding them.

How do you clearly show tasks being divided for multi-threading?
"
2847386|"Python String and Integer concatenation"|"I want to create string using integer appended to it, in a for loop.  Like this:

<code>for i in range(1,11):
  string=""string""+i
</code>

But it returns an error:

<code>TypeError: unsupported operand type(s) for +: 'int' and 'str'
</code>

What's the best way to concatenate the String and Integer?
"
2915471|"Install a Python package into a different directory using pip?"|"I know the obvious answer is to use virtualenv and virtualenvwrapper, but for various reasons I can't/don't want to do that.

So how do I modify the command

<code>pip install package_name
</code>

to make <code>pip</code> install the package somewhere other than the default <code>site-packages</code>?
"
2918362|"writing string to a file on a new line every time?"|"I want to append a newline to my string every time I call <code>file.write()</code>. What's the easiest way to do this in Python?
"
2952187|"Getting ""Error loading MySQLdb module: No module named MySQLdb"" - have tried previously posted solutions"|"This is a much discussed issue for OSX 10.6 users, but I haven't been able to find a solution that works. Here's my setup:

Python 2.6.1 64bit
Django 1.2.1
MySQL 5.1.47 osx10.6 64bit

I create a virtualenvwrapper with --no-site-packages, then installed Django. When I activate the virtualenv and run python manage.py syncdb, I get this error:

<code>Traceback (most recent call last):
File ""manage.py"", line 11, in &lt;module&gt;
  execute_manager(settings)
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/core/management/__init__.py"", line 438, in execute_manager
  utility.execute()
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/core/management/__init__.py"", line 379, in execute
  self.fetch_command(subcommand).run_from_argv(self.argv)
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/core/management/__init__.py"", line 257, in fetch_command
  klass = load_command_class(app_name, subcommand)
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/core/management/__init__.py"", line 67, in load_command_class
  module = import_module('%s.management.commands.%s' % (app_name, name))
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/utils/importlib.py"", line 35, in import_module
  __import__(name)
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/core/management/commands/syncdb.py"", line 7, in &lt;module&gt;
from django.core.management.sql import custom_sql_for_model, emit_post_sync_signal
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/core/management/sql.py"", line 5, in &lt;module&gt;
from django.contrib.contenttypes import generic
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/contrib/contenttypes/generic.py"", line 6, in &lt;module&gt;
  from django.db import connection
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/db/__init__.py"", line 75, in &lt;module&gt;
  connection = connections[DEFAULT_DB_ALIAS]
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/db/utils.py"", line 91, in __getitem__
  backend = load_backend(db['ENGINE'])
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/db/utils.py"", line 32, in load_backend
  return import_module('.base', backend_name)
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/utils/importlib.py"", line 35, in import_module
  __import__(name)
File ""/Users/joerobinson/.virtualenvs/dj_tut/lib/python2.6/site-packages/django/db/backends/mysql/base.py"", line 14, in &lt;module&gt;
  raise ImproperlyConfigured(""Error loading MySQLdb module: %s"" % e)
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb
</code>

I've also installed the MySQL for Python adapter, but to no avail (maybe I installed it improperly?). 

Anyone dealt with this before?
"
2953462|"Pinging servers in Python"|"In Python, is there a way to ping a server through ICMP and return TRUE if the server responds, or FALSE if there is no response?
"
2958684|"Python division"|"I was trying to normalize a set of numbers from -100 to 0 to a range of 10-100 and was having problems only to notice that even with no variables at all, this does not evaluate the way I would expect it to:

<code>&gt;&gt;&gt; (20-10) / (100-10)
0
</code>

Float division doesn't work either:

<code>&gt;&gt;&gt; float((20-10) / (100-10))
0.0
</code>

If either side of the division is cast to a float it will work:

<code>&gt;&gt;&gt; (20-10) / float((100-10))
0.1111111111111111
</code>

Each side in the first example is evaluating as an int which means the final answer will be cast to an int. Since 0.111 is less than .5, it rounds to 0.  It is not transparent in my opinion, but I guess that's the way it is.

What is the explanation?
"
2960772|"Putting a variable inside a string (python)"|"Hi I am quite new to python and this is probably quite a basic question but the help would be much appreciated.

I would like to put an int within a string. This is what I am doing at the moment..

<code>end = smooth(data,window_len=40)
plot.plot(time[0:len(end)],end)
plot.savefig('hanning(40).pdf') #problem line
</code>

I have to run the program for several different numbers instead of the two 40's. So I'd like to do a loop but inserting the variable like this doesn't work:

<code>plot.savefig('hanning',num,'.pdf')
</code>

Thanks!
"
2967194|"open() in Python does not create a file if it doesn't exist"|"What is the best way to open a file as read/write if it exists, or if it does not, then create it and open it as read/write? From what I read, <code>file = open('myfile.dat', 'rw')</code> should do this, right?

It is not working for me (Python 2.6.2) and I'm wondering if it is a version problem, or not supposed to work like that or what.

The bottom line is, I just need a solution for the problem. I am curious about the other stuff, but all I need is a nice way to do the opening part.

UPDATE: the enclosing directory was writeable by user and group, not other (I'm on a Linux system... so permissions 775 in other words), and the exact error was:


  IOError: no such file or directory.

"
2972212|"Creating an empty list in Python"|"What is the best way to create a new empty list in Python?

<code>l = [] 
</code>

or

<code>l = list()
</code>

I am asking this because of two reasons:


Technical reasons, as to which is faster. (creating a class causes overhead?)
Code readability - which one is the standard convention.

"
2988017|"String comparison in Python: is vs. =="|"I noticed a Python script I was writing was acting squirrelly, and traced it to an infinite loop, where the loop condition was <code>while line is not ''</code>. Running through it in the debugger, it turned out that line was in fact <code>''</code>. When I changed it to <code>!=''</code> rather than <code>is not ''</code>, it worked fine. 

Also, is it generally considered better to just use '==' by default, even when comparing int or Boolean values? I've always liked to use 'is' because I find it more aesthetically pleasing and pythonic (which is how I fell into this trap...), but I wonder if it's intended to just be reserved for when you care about finding two objects with the same id.
"
2998215|"If Python is interpreted, what are .pyc files?"|"I've been given to understand that Python is an interpreted language... However, when I look at my Python source code I see <code>.pyc</code> files, which Windows identifies as ""Compiled Python Files"". Where do these come in?
"
3013449|"List filtering: list comprehension vs. lambda + filter"|"I happened to find myself having a basic filtering need: I have a list and I have to filter it by an attribute of the items.

My code looked like this:

<code>my_list = [x for x in my_list if x.attribute == value]
</code>

But then I thought, wouldn't it be better to write it like this?

<code>my_list = filter(lambda x: x.attribute == value, my_list)
</code>

It's more readable, and if needed for performance the lambda could be taken out to gain something.  

Question is: are there any caveats in using the second way? Any performance difference? Am I missing the Pythonic Way™ entirely and should do it in yet another way (such as using itemgetter instead of the lambda)?
"
3061761|"Numpy array dimensions"|"I'm currently trying to learn Numpy and Python. Given the following array:

<code>import numpy as N
a = N.array([[1,2],[1,2]])
</code>

Is there a function that returns the dimensions of <code>a</code> (e.g.a is a 2 by 2 array)?

<code>size()</code> returns 4 and that doesn't help very much. 
"
3097866|"Access an arbitrary element in a dictionary in Python"|"If a <code>dict</code> is not empty, I access an arbitrary element as:

<code>dict[dict.keys()[0]]
</code>

Is there any better way to do this?
"
3121979|"How to sort (list/tuple) of lists/tuples?"|"I have some data either in list contains lists, or list contains tuples.

<code>data = [[1,2,3], [4,5,6], [7,8,9]]
data = [(1,2,3), (4,5,6), (7,8,9)]
</code>

And I want to sort by the 2nd element in the subset. Meaning, sorting by 2,5,8 where 2 is from (1,2,3), 5 is from (4,5,6). What is the common way to do this? Should I store tuples or lists in my list? Since tuples are more inflexible.
"
3199171|"append multiple values for one key in Python dictionary"|"I am new to python and I have a list of years and values for each year. What I want to do is check if the year already exists in a dictionary and if it does, append the value to that list of values for the specific key.

So for instance, I have a list of years and have one value for each year:

<code>2010  
2  
2009  
4  
1989  
8  
2009  
7  
</code>

What I want to do is populate a dictionary with the years as keys and those single digit numbers as values. However, if I have 2009 listed twice, I want to append that second value to my list of values in that dictionary, so I want:  

<code>2010: 2  
2009: 4, 7  
1989: 8  
</code>

Right now I have the following:  

<code>d = dict()  
years = []  

(get 2 column list of years and values)

for line in list:    
    year = line[0]   
    value = line[1]  

for line in list:  
    if year in d.keys():  
        d[value].append(value)  
    else:  
        d[value] = value  
        d[year] = year  
</code>
"
3207219|"How do I list all files of a directory?"|"How can I list all files of a directory in Python and add them to a list?
"
3249524|"Print in one line dynamically"|"I would like to make several statements that give standard output without seeing newlines in between statements.

Specifically, suppose I have:

<code>for item in range(1,100):
    print item
</code>

The result is:

<code>1
2
3
4
.
.
.
</code>

How get this to instead look like:

<code>1 2 3 4 5 ...
</code>

Even better, is it possible to print the single number over the last number, so only one number is on the screen at a time?
"
3263672|"Python - The difference between sys.stdout.write and print"|"Are there situations in which <code>sys.stdout.write()</code> is preferable to <code>print</code>? 

(Examples: better performance; code that makes more sense)
"
3277503|"How do I read a file line-by-line into a list?"|"How do I read every line of a file in Python and store each line as an element in a list? 

I want to read the file line by line and append each line to the end of the list.
"
3294889|"Iterating over dictionaries using 'for' loops"|"I am a bit puzzled by the following code:

<code>d = {'x': 1, 'y': 2, 'z': 3} 
for key in d:
    print key, 'corresponds to', d[key]
</code>

What I don't understand is the <code>key</code> portion. How does Python recognize that it needs only to read the key from the dictionary? Is <code>key</code> a special word in Python? Or is it simply a variable?
"
3345202|"Getting user input"|"I am running this:

<code>import csv
import sys
reader = csv.reader(open(sys.argv[0], ""rb""))
for row in reader:
    print row
</code>

And I get this in response:

<code>['import csv']
['import sys']
['reader = csv.reader(open(sys.argv[0]', ' ""rb""))']
['for row in reader:']
['    print row']
&gt;&gt;&gt; 
</code>

For the <code>sys.argv[0]</code> I would like it to prompt me to enter a filename.

How do I get it to prompt me to enter a filename?
"
3387655|"Safest way to convert float to integer in python?"|"Python's math module contain handy functions like <code>floor</code> &amp; <code>ceil</code>. These functions take a floating point number and return the nearest integer below or above it. However these functions return the answer as a floating point number. For example:

<code>import math
f=math.floor(2.3)
</code>

Now <code>f</code> returns:

<code>2.0
</code>

What is the safest way to get an integer out of this float, without running the risk of rounding errors (for example if the float is the equivalent of 1.99999) or perhaps I should use another function altogether?
"
3394835|"*args and **kwargs?"|"So I have difficulty with the concept of *args and **kwargs.

So far I have learned that:


<code>*args</code> = list of arguments -as positional arguments
<code>**kwargs</code> = dictionary - whose keys become separate keyword arguments and the values become values of these arguments.


??

To be honest I don't understand and don't get for what programming task this would helpful. (I am sure there is, but I can't get an understanding of it.)

Maybe:

I think to enter lists and dictionaries as arguments of a function AND at the same time as a wildcard, so I can pass ANY argument?

Is there a simple example on which to explain how <code>*args</code> and <code>**kwargs</code> are used?

Also the tutorial I run through used just the ""*"" and a variable name. 

Is <code>*args</code> and <code>**kwargs</code> just a placeholder or do you use exactly <code>*args</code> and <code>**kwargs</code> in the code?
"
3402168|"Permanently add a directory to PYTHONPATH"|"Whenever I use <code>sys.path.append</code>, the new directory will be added. However, once I close python, the list will revert to the previous (default?) values. How do I permanently add a directory to PYTHONPATH?
"
3437059|"Does Python have a string 'contains' substring method?"|"I'm looking for a <code>string.contains</code> or <code>string.indexof</code> method in Python.

I want to do:

<code>if not somestring.contains(""blah""):
   continue
</code>
"
3459098|"Create List of Single Item Repeated n Times in Python"|"I know a list comprehension will do this, but I was wondering if there is an even shorter (and more Pythonic?) approach.

I want to create a series of lists, all of varying length. Each list will contain the same element e, repeated n times (where n = length of the list). How do I create the lists, without doing

<code>[e for number in xrange(n)]
</code>

for each list?
"
3462143|"Get difference between two lists"|"I have two lists in Python, like these:

<code>temp1 = ['One', 'Two', 'Three', 'Four']
temp2 = ['One', 'Two']
</code>

I need to create a third list with items from the first list which aren't present in the second one. From the example I have to get:

<code>temp3 = ['Three', 'Four']
</code>

Are there any fast ways without cycles and checking?
"
3501382|"Checking whether a variable is an integer or not"|"How do I check whether a variable is an integer?
"
3503879|"Assign output of os.system to a variable and prevent it from being displayed on the screen"|"I want to assign the output of a command I run using <code>os.system</code> to a variable and prevent it from being output to the screen. But, in the below code ,the output is sent to the screen and the value printed for <code>var</code> is 0, which I guess signifies whether the command ran successfully or not. Is there any way to assign the command output to the variable and also stop it from being displayed on the screen?

<code>var = os.system(""cat /etc/services"")
print var #Prints 0
</code>
"
3518778|"How to read csv into record array in numpy?"|"I wonder if there is a direct way to import the contents of a csv file into a record array, much in the way that R's <code>read.table()</code>, <code>read.delim()</code>, and <code>read.csv()</code> family imports data to R's data frame? 

Or is the best way to use csv.reader() and then apply something like <code>numpy.core.records.fromrecords()</code>?
"
3528146|"Convert decimal to binary in python"|"Is there any module or function in python i can use to convert a decimal number to its binary equivalent ?
I am able to convert binary to decimal using int('[binary_value]',2),so any way to do the reverse without writing the code to do it myself ?

Thank You
"
3545331|"How can I get dictionary key as variable directly in Python (not by searching from value)?"|"Sorry for this basic question but my searches on this are not turning up anything other than how to get a dictionary's key based on its value which I would prefer not to use as I simply want the text/name of the key and am worried that searching by value may end up returning 2 or more keys if the dictionary has a lot of entries... what I am trying to do is this:

<code>mydictionary={'keyname':'somevalue'}
for current in mydictionary:

   result = mydictionary.(some_function_to_get_key_name)[current]
   print result
   ""keyname""
</code>

The reason for this is that I am printing these out to a document and I want to use the key name and the value in doing this

I have seen the method below but this seems to just return the key's value

<code>get(key[, default])
</code>
"
3559559|"How to delete a character from a string using python?"|"There is a string, for example <code>EXAMPLE</code>

How can I remove the middle character i.e. <code>M</code> from it. I don't need the code, what I want to know is


Do strings in python end in any special character?
Which is a better way - shifting everything right to left starting from the middle character OR creation of a new string and not copying the middle character?

"
3561691|"python: SyntaxError: EOL while scanning string literal"|"I have the above mentioned error in <code>s1=""some very long string............""</code> 

Anyone know what i am doing wrong?
"
3682748|"Converting unix timestamp string to readable date in Python"|"I have a string representing a unix timestamp (i.e. ""1284101485"") in Python, and I'd like to convert it to a readable date. When I use <code>time.strftime</code>, I get a <code>TypeError</code>:

<code>&gt;&gt;&gt;import time
&gt;&gt;&gt;print time.strftime(""%B %d %Y"", ""1284101485"")

Traceback (most recent call last):
  File ""&lt;stdin&gt;"", line 1, in &lt;module&gt;
TypeError: argument must be 9-item sequence, not str
</code>
"
3701646|"How to add to the pythonpath in windows 7?"|"I have a directory which hosts all of my Django apps (<code>C:\My_Projects</code>). I want to add this directory to my <code>pythonpath</code> so I can call the apps directly.

I have tried adding <code>C:\My_Projects\;</code> to my <code>Path</code> variable from the Windows GUI (<code>My Computer &gt; Properties &gt; Advanced System Settings &gt; Environment Variables</code>). But it still doesn't read the coltrane module and generates this error:


  Error: No module named coltrane

"
3702675|"How to print the full traceback without halting the program?"|"I'm writing a program that parses 10 websites, locates data files, saves the files, and then parses them to make data that can be readily used in the NumPy library. There are tons of errors this file encounters through bad links, poorly formed XML, missing entries, and other things I've yet to categorize. I initially made this program to handle errors like this:

<code>try:
    do_stuff()
except:
    pass
</code>

But now I want to log errors:

<code>try:
    do_stuff()
except Exception, err:
    print Exception, err
</code>

Note this is printing to a log file for later review. This usually prints very useless data. What I want is to print the exact same lines printed when the error triggers without the try-except intercepting the exception, but I don't want it to halt my program since it is nested in a series of for loops that I would like to see to completion.
"
3768895|"How to make a class JSON serializable"|"How to make a Python class serializable?  

A simple class:

<code>class FileItem:
    def __init__(self, fname):
        self.fname = fname
</code>

What should I do to be able to get output of:

<code>json.dumps()
</code>

Without an error (<code>FileItem instance at ... is not JSON serializable</code>)
"
3777861|"setting y-axis limit in matplotlib"|"I need help with setting the limits of y-axis on matplotlib. Here is the code that I tried, unsuccessfully.

<code>import matplotlib.pyplot as plt

plt.figure(1, figsize = (8.5,11))
plt.suptitle('plot title')
ax = []
aPlot = plt.subplot(321, axisbg = 'w', title = ""Year 1"")
ax.append(aPlot)
plt.plot(paramValues,plotDataPrice[0], color = '#340B8C', 
     marker = 'o', ms = 5, mfc = '#EB1717')
plt.xticks(paramValues)
plt.ylabel('Average Price')
plt.xlabel('Mark-up')
plt.grid(True)
plt.ylim((25,250))
</code>

With the data I have for this plot, I get y-axis limits of 20 and 200. However, I want the limits 20 and 250.
"
3781851|"Run a python script from another python script, passing in args"|"I want to run a Python script from another Python script. I want to pass variables like I would using the command line.

For example, I would run my first script that would iterate through a list of values (0,1,2,3) and pass those to the 2nd script <code>script2.py 0</code> then  <code>script2.py 1</code>, etc.

I found SO 1186789 which is a similar question but ars's answer calls a function, where as I want to run the whole script not just a function, and balpha's answer calls the script but with no args. I altered this to something like the below as a test: 

<code>execfile(""script2.py 1"")
</code>

But it is not accepting variables properly.  When I print out the <code>sys.argv</code> in script2.py it is the original command call to first script ""['C:\script1.py'].

I don't really want to change the original script (i.e. script2.py in my example) since I don't own it.

I figure there must be a way to do this, I am just confused how you do it.  
"
3791465|"Python, os.system for command-line call (linux) not returning what it should?"|"I need to make some command line calls to linux and get the return from this, however doing it as below is just returning <code>0</code> when it should return a time value, like <code>00:08:19</code>, I am testing the exact same call in regular command line and it returns the time value <code>00:08:19</code> so I am confused as to what I am doing wrong as I thought this was how to do it in python. Any advice is appreciated.

<code>import os
retvalue = os.system(""ps -p 2993 -o time --no-headers"")
print retvalue
</code>
"
3819449|"How to uninstall Python 2.7 on a Mac OS X 10.6.4?"|"I want to completely remove Python 2.7 from my Mac OS X 10.6.4. I managed to remove the entry from the PATH variable by reverting my .bash_profile. But I also want to remove all directories, files, symlinks, and entries that got installed by the Python 2.7 install package. I've got the install package from http://www.python.org/. What directories/files/configuration file entries do I need to remove? Is there a list somewhere?
"
3845423|"Remove empty strings from a list of strings"|"I want to remove all empty strings from a list of strings in python.

My idea looks like this:

<code>while '' in str_list:
    str_list.remove('')
</code>

Is there any more pythonic way to do this?
"
3887381|"TypeError: 'NoneType' object is not iterable in Python"|"What does error <code>TypeError: 'NoneType' object is not iterable</code> mean?

I am getting it on this Python code:

<code>def write_file(data,filename):   #creates file and writes list to it
  with open(filename,'wb') as outfile:
    writer=csv.writer(outfile)
    for row in data:             ##ABOVE ERROR IS THROWN HERE
      writer.writerow(row)
</code>
"
3890621|"how does multiplication differ for NumPy Matrix vs Array classes?"|"The numpy docs recommend using array instead of matrix for working with matrices. However, unlike octave (which I was using till recently), * doesn't perform matrix multiplication, you need to use the function matrixmultipy(). I feel this makes the code very unreadable.

Does anybody share my views, and has found a solution?
"
3899980|"How to change the font size on a matplotlib plot"|"How does one change the font size for all elements (ticks, labels, title) on a matplotlib plot?

I know how to change the tick label sizes, this is done with:

<code>import matplotlib 
matplotlib.rc('xtick', labelsize=20) 
matplotlib.rc('ytick', labelsize=20) 
</code>

But how does one change the rest?
"
3925614|"How do you read a file into a list in Python?"|"I want to prompt a user for a number of random numbers to be generated and saved to a file.  He gave us that part.  The part we have to do is to open that file, convert the numbers into a list, then find the mean, standard deviation, etc without using the easy built in python tools.

I've tried using <code>open</code> but it gives me invalid syntax (the file name I chose was ""numbers"" and it saved into <code>""My Documents""</code> automatically, so I tried <code>open(numbers, 'r')</code> and <code>open(C:\name\MyDocuments\numbers, 'r')</code> and neither one worked).
"
3939361|"Remove specific characters from a string in python"|"I'm trying to remove specific characters from a string using python. This is the code I'm using right now. Unfortunately it appears to do nothing to the string.

<code>for char in line:
    if char in "" ?.!/;:"":
        line.replace(char,'')
</code>

How do I do this properly?
"
3940128|"How can I reverse a list in python?"|"How can I do this in python?

<code>array = [0,10,20,40]
for (i = array.length() - 1 ;i &gt;= 0; i--)
</code>

I need to have the elements of an array but from the end to the beginning.
"
3964681|"Find all files in a directory with extension .txt in Python"|"How can I find all the files in a directory having the extension <code>.txt</code> in python?
"
3965104|"not None test in Python"|"Out of these not None tests.

<code>if val != None:

if not (val is None):

if val is not None:
</code>

Which one is preferable, and why?
"
3987041|"Python: Run function from the command line"|"I have below code in my file:

<code>def hello():
    return 'Hi :)'
</code>

How would I run this from the command line?
"
3996904|"Generate random integers between 0 and 9"|"How can I generate random integers between 0 and 9 (inclusive) in Python?

i.e. <code>0</code>, <code>1</code>, <code>2</code>, <code>3</code>, <code>4</code>, <code>5</code>, <code>6</code>, <code>7</code>, <code>8</code>, <code>9</code>
"
4041238|"Why use def main()?"|"
  Possible Duplicate:
  What does <code>if __name__== ""__main__""</code> do?  




I've seen some code samples and tutorials that use

<code>def main():
    # my code here

if __name__ == ""__main__"":
    main()
</code>

But why? Is there any reason not do define your functions at the top of the file, then just write code under it? ie

<code>def my_function()
    # my code here

def my_function_two()
    # my code here

# some code
# call function
# print(something)
</code>

I just wonder if there is any rhyme to the main?
"
4056768|"How to declare array of zeros in python (or an array of a certain size)"|"I am trying to build a histogram of counts... so I create buckets.
I know I could just go through and append a bunch of zeros i.e something along these lines:

<code>buckets = []
for i in xrange(0,100):
    buckets.append(0)
</code>

Is there a  more elegant way to do it? I feel like there should be a way to just declare an array of a certain size.

I know numpy has <code>numpy.zeros</code> but I want the more general solution
"
4071396|"Split by comma and strip whitespace in Python"|"I have some python code that splits on comma, but doesn't strip the whitespace:

<code>&gt;&gt;&gt; string = ""blah, lots  ,  of ,  spaces, here ""
&gt;&gt;&gt; mylist = string.split(',')
&gt;&gt;&gt; print mylist
['blah', ' lots  ', '  of ', '  spaces', ' here ']
</code>

I would rather end up with whitespace removed like this:

<code>['blah', 'lots', 'of', 'spaces', 'here']
</code>

I am aware that I could loop through the list and strip() each item but, as this is Python, I'm guessing there's a quicker, easier and more elegant way of doing it.
"
4130027|"Python count elements in list"|"I am a newbe to Python..
I am trying to find a simple way of getting a count of the number of elements in a list 
e.g. 

<code>MyList = [""a"", ""b"", ""c""]
</code>

So I want to know there are three.
I am surely missing something.
"
4142151|"How to import the class within the same directory or sub directory?"|"I have a directory that stores all the .py files.

<code>bin/
   main.py
   user.py # where class User resides
   dir.py # where class Dir resides
</code>

I want to use classes from user.py and dir.py in main.py.
How can I import these Python classes into main.py?
Furthermore, how can I import class <code>User</code> if user.py is in a sub directory?

<code>bin/
    dir.py
    main.py
    usr/
        user.py
</code>
"
4172448|"Is it possible to break a long line to multiple lines in Python"|"Just like C, you can break a long line into multiple short lines. But in Python, if I do this, there will be an indent error... Is it possible?
"
4182603|"How to convert a string to utf-8 in Python"|"I have a browser which sends utf-8 characters to my Python server, but when I retrieve it from the query string, the encoding that Python returns is ASCII. How can I convert the plain string to utf-8?

NOTE: The string passed from the web is already UTF-8 encoded, I just want to make Python to treat it as UTF-8 not ASCII.
"
4183506|"Python list sort in descending order"|"How can I sort this list in descending order?

<code>timestamp = [
    ""2010-04-20 10:07:30"",
    ""2010-04-20 10:07:38"",
    ""2010-04-20 10:07:52"",
    ""2010-04-20 10:08:22"",
    ""2010-04-20 10:08:22"",
    ""2010-04-20 10:09:46"",
    ""2010-04-20 10:10:37"",
    ""2010-04-20 10:10:58"",
    ""2010-04-20 10:11:50"",
    ""2010-04-20 10:12:13"",
    ""2010-04-20 10:12:13"",
    ""2010-04-20 10:25:38""
]
</code>
"
4256107|"running bash commands in python"|"On my local machine I run a python script which contains this line

<code>bashCommand = ""cwm --rdf test.rdf --ntriples &gt; test.nt""
os.system(bashCommand)
</code>

This works fine.

Then I run the same code on a server and I get the following error message

<code>'import site' failed; use -v for traceback
Traceback (most recent call last):
File ""/usr/bin/cwm"", line 48, in &lt;module&gt;
from swap import  diag
ImportError: No module named swap
</code>

So what I did then is I inserted a ""print bashCommand"" which prints me then the command in the terminal before it runs it with os.system().

Of course I get again the error (caused by os.system(bashCommand)) but before that error it prints the command in the terminal. Then I just copied that output and did a copy paste into the terminal and hit enter and it works...

Does anyone have a clue what's going on :(?
"
4271740|"How can I use Python to get the system hostname?"|"I'm writing a chat program for a local network. I would like be able to identify computers and get the user-set computer name with Python.
"
4288973|"What's the difference between %s and %d in Python string formatting?"|"I don't understand what <code>%s</code> and <code>%d</code> do and how they work.
"
4289331|"Python: Extract numbers from a string"|"I would extract all the numbers contained in a string. Which is the better suited for the purpose, regular expressions or the <code>isdigit()</code> method?

Example:

<code>line = ""hello 12 hi 89""
</code>

Result:

<code>[12, 89]
</code>
"
4344017|"How can I get the concatenation of two lists in Python without modifying either one?"|"In Python, the only way I can find to concatenate two lists is <code>list.extend</code>, which modifies the first list. Is there any concatenation function that returns its result without modifying its arguments?
"
4362586|"sum a list of numbers in Python"|"If I have a list of numbers such as <code>[1,2,3,4,5...]</code> and I want to calculate <code>(1+2)/2</code> and for the second, <code>(2+3)/2</code> and the third,
<code>(3+4)/2</code>, and so on.

How can I do that?
I would like to sum the first number with the second and divide it by 2, then sum the second with the third and divide by 2, and so on.

Also, how can I sum a list of numbers?

<code>a = [1,2,3,4,5,...]
</code>

Is it:

<code>b = sum(a)
print b
</code>

to get one number?
This doesn't work for me. 
Help me please.
"
4377109|"Shell Script: Execute a python program from within a shell script"|"I've tried googling the answer but with no luck.

I need to use my works supercomputer server, but for my python script to run, it must be executed via a shell script.

For example I want <code>job.sh</code> to execute <code>python_script.py</code>

How can this be accomplished?
"
4383571|"Importing files from different folder"|"I have the following folder structure.

<code>application/app/folder/file.py</code>

and I want to import some functions from file.py in another Python file which resides in

<code>application/app2/some_folder/some_file.py</code>

I've tried

<code>from application.app.folder.file import func_name</code>

and some other various attempts but so far I couldn't manage to import properly. How can I do this?
"
4426663|"How do I remove the first Item from a Python list?"|"I have the list <code>[0, 1, 2, 3, 4]</code> I'd like to make it into <code>[1, 2, 3, 4]</code>. How do I go about this? 
"
4432208|"How does % work in Python?"|"What does the <code>%</code> in a calculation? I can't seem to work out what it does.

Does it work out a percent of the calculation for example: <code>3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6</code> is apparently equal to 7. How?
"
4435169|"Good way to append to a string"|"I want an efficient way to append string to another.

Is there any good built-in method to use?
"
4455076|"How to access the ith column of a NumPy multidimensional array?"|"Suppose I have:

<code>test = numpy.array([[1, 2], [3, 4], [5, 6]])
</code>

<code>test[i]</code> gets me ith line of the array (eg <code>[1, 2]</code>). How can I access the ith column? (eg <code>[1, 3, 5]</code>). Also, would this be an expensive operation?
"
4481724|"Convert a list of characters into a string"|"If I have a list of chars:

<code>a = ['a','b','c','d']
</code>

How do I convert it into a single string?

<code>a = 'abcd'
</code>
"
4534438|"TypeError: 'module' object is not callable"|"<code>File ""C:\Users\Administrator\Documents\Mibot\oops\blinkserv.py"", line 82, in __init__
    self.serv = socket(AF_INET,SOCK_STREAM)
TypeError: 'module' object is not callable
</code>

Why am I getting this error?
I'm confused.

What do you need to know to answer my question?
"
4547274|"Convert a python dict to a string and back"|"I am writing a program that stores data in a dictionary object, but this data needs to be saved at some point during the program execution and loaded back into the dictionary object when the program is run again.
How would I convert a dictionary object into a string that can be written to a file and loaded back into a dictionary object? This will hopefully support dictionaries containing dictionaries.
"
4576115|"Convert a list to a dictionary in Python"|"Let's say I have a list <code>a</code> in Python whose entries conveniently map to a dictionary. Each even element represents the key to the dictionary, and the following odd element is the value

for example,

<code>a = ['hello','world','1','2']
</code>

and I'd like to convert it to a dictionary <code>b</code>, where 

<code>b['hello'] = 'world'
b['1'] = '2'
</code>

What is the syntactically cleanest way to accomplish this?
"
4664850|"Find all occurrences of a substring in Python"|"Python has <code>string.find()</code> and <code>string.rfind()</code> to get the index of a substring in string.

I wonder, maybe there is something like <code>string.find_all()</code> which can return all founded indexes (not only first from beginning or first from end)?

For example:

<code>string = ""test test test test""

print string.find('test') # 0
print string.rfind('test') # 15

#that's the goal
print string.find_all('test') # [0,5,10,15]
</code>
"
4666973|"How to extract a substring from inside a string in Python?"|"Let's say I have a string <code>'gfgfdAAA1234ZZZuijjk'</code> and I want to extract just the <code>'1234'</code> part.

I only know what will be the few characters directly before <code>AAA</code>, and after <code>ZZZ</code> the part I am interested in <code>1234</code>.

With <code>sed</code> it is possible to do something like this with a string:

<code>echo ""$STRING"" | sed -e ""s|.*AAA\(.*\)ZZZ.*|\1|""
</code>

And this will give me <code>1234</code> as a result.

How to do the same thing in Python?
"
4675728|"Redirect stdout to a file in Python?"|"How do I redirect stdout to an arbitrary file in Python?

When a long-running Python script (e.g, web application) is started from within the ssh session and backgounded, and the ssh session is closed, the application will raise IOError and fail the moment it tries to write to stdout. I needed to find a way to make the application and modules output to a file rather than stdout to prevent failure due to IOError. Currently, I employ nohup to redirect output to a file, and that gets the job done, but I was wondering if there was a way to do it without using nohup, out of curiosity.

I have already tried <code>sys.stdout = open('somefile', 'w')</code>, but this does not seem to prevent some external modules from still outputting to terminal (or maybe the <code>sys.stdout = ...</code> line did not fire at all). I know it should work from simpler scripts I've tested on, but I also didn't have time yet to test on a web application yet.
"
4693120|"Use of ""global"" keyword in Python"|"What I understand from reading the documentation is that Python has a separate namespace for functions, and if I want to use a global variable in that function, I need to use <code>global</code>.

I'm using Python 2.7 and I tried this little test

<code>&gt;&gt;&gt; sub = ['0', '0', '0', '0']
&gt;&gt;&gt; def getJoin():
...     return '.'.join(sub)
...
&gt;&gt;&gt; getJoin()
'0.0.0.0'
</code>

It seems things are working fine even without <code>global</code>. I was able to access global variable without any problem.

Am I missing anything? Also, following is from Python documentation:


  Names listed in a global statement
  must not be defined as formal
  parameters or in a for loop control
  target, class definition, function
  definition, or import statement.


While formal parameters and class definition make sense to me, I'm not able to understand the restriction on for loop control target and function definition.
"
4700614|"How to put the legend out of the plot"|"I have a series of 20 plots (not subplots) to be made in a single figure.  I want the legend to be outside of the box.  At the same time, I do not want to change the axes, as the size of the figure gets reduced.  Kindly help me for the following queries:


I want to keep the legend box outside the plot area. (I want the legend to be outside at the right side of the plot area).
Is there anyway that I reduce the font size of the text inside the legend box, so that the size of the legend box will be small.

"
4706499|"How do you append to a file?"|"How do you append to the file instead of overwriting it? Is there a special function that appends to the file?
"
4750806|"How do I install pip on Windows?"|"<code>pip</code> is a replacement for <code>easy_install</code>. But should I install <code>pip</code> using <code>easy_install</code> on Windows?  Is there a better way?
"
4760215|"Running shell command from Python and capturing the output"|"I want to write a function that will execute a shell command and return its output as a string, no matter, is it an error or success message. I just want to get the same result that I would have gotten with the command line.

What would be a code example that would do such a thing?

For example:

<code>def run_command(cmd):
    # ??????

print run_command('mysqladmin create test -uroot -pmysqladmin12')
# Should output something like:
# mysqladmin: CREATE DATABASE failed; error: 'Can't create database 'test'; database exists'
</code>
"
4783810|"Install tkinter for Python"|"I am trying to import Tkinter. However, I get an error stating that Tkinter has not been installed:


  ImportError: No module named _tkinter, please install the python-tk package


I could probably install it using synaptic manager (can I?), however, I would have to install it on every machine I program on. Would it be possible to add the Tkinter library into my workspace and reference it from there?
"
4843158|"Check if a Python list item contains a string inside another string"|"I have a list:

<code>my_list = ['abc-123', 'def-456', 'ghi-789', 'abc-456']
</code>

and want to search for items that contain the string <code>'abc'</code>. How can I do that?

<code>if 'abc' in my_list:
</code>

would check if <code>'abc'</code> exists in the list but it is a part of <code>'abc-123'</code> and <code>'abc-456'</code>, <code>'abc'</code> does not exist on its own. So how can I get all items that contain <code>'abc'</code> ?
"
4843173|"How to check if type of a variable is string?"|"Is there a way to check if the type of a variable in python is string.. like

<code>isinstance(x,int);
</code>

for integer values?
"
4906977|"Access environment variables from Python"|"I set an environment variable that I want to access in my Python application.  How do I get this value?
"
4915920|"How to delete an item in a list if it exists?"|"I am getting <code>new_tag</code> from a form text field with <code>self.response.get(""new_tag"")</code> and <code>selected_tags</code> from checkbox fields with 

<code>self.response.get_all(""selected_tags"")
</code>

I combine them like this:

<code>tag_string = new_tag
new_tag_list = f1.striplist(tag_string.split("","") + selected_tags)
</code>

(<code>f1.striplist</code> is a function that strips white spaces inside the strings in the list.)

But in the case that <code>tag_list</code> is empty (no new tags are entered) but there are some <code>selected_tags</code>, <code>new_tag_list</code> contains an empty string <code>"" ""</code>.

For example, from <code>logging.info</code>:

<code>new_tag
selected_tags[u'Hello', u'Cool', u'Glam']
new_tag_list[u'', u'Hello', u'Cool', u'Glam']
</code>

How do I get rid of the empty string?

If there is an empty string in the list:

<code>&gt;&gt;&gt; s = [u'', u'Hello', u'Cool', u'Glam']
&gt;&gt;&gt; i = s.index("""")
&gt;&gt;&gt; del s[i]
&gt;&gt;&gt; s
[u'Hello', u'Cool', u'Glam']
</code>

But if there is no empty string:

<code>&gt;&gt;&gt; s = [u'Hello', u'Cool', u'Glam']
&gt;&gt;&gt; if s.index(""""):
        i = s.index("""")
        del s[i]
    else:
        print ""new_tag_list has no empty string""
</code>

But this gives:

<code>Traceback (most recent call last):
  File ""&lt;pyshell#30&gt;"", line 1, in &lt;module&gt;
    if new_tag_list.index(""""):
        ValueError: list.index(x): x not in list
</code>

Why does this happen, and how do I work around it?
"
4934806|"How can I find script's directory with Python?"|"Consider the following Python code:

<code>import os
print os.getcwd()
</code>

I use <code>os.getcwd()</code> to get the script file's directory location. When I run the script from the command line it gives me the correct path whereas when I run it from a script run by code in a Django view it prints <code>/</code>.

How can I get the path to the script from within a script run by a Django view?

UPDATE:
Summing up the answers thus far - <code>os.getcwd()</code> and <code>os.path.abspath()</code> both give the current working directory which may or may not be the directory where the script resides. In my web host setup <code><code>__file__</code></code> gives only the filename without the path.

Isn't there any way in Python to (always) be able to receive the path in which the script resides?
"
4940032|"Search for string in txt file Python"|"I want to check if a string is in a text file. If it is, do X. If it's not, do Y. However, this code always returns <code>True</code> for some reason. Can anyone see what is wrong?

<code>def check():
    datafile = file('example.txt')
    found = False
    for line in datafile:
        if blabla in line:
            found = True
            break

check()
if True:
    print ""true""
else:
    print ""false""
</code>
"
4960208|"Python 2.7 getting user input and manipulating as string without quotations"|"I want to get a string from a user, and then to manipulate it.

<code>testVar = input(""Ask user for something."")
</code>

Is there a way for testVar to be a string without me having the user type his response in quotes?  i.e. ""Hello"" vs. Hello

If the user types in Hello, I get the following error:

NameError: name 'Hello' is not defined
"
4978787|"How to split a string into array of characters with Python?"|"I've tried to look around the web for answers to splitting a string into an array of characters but I can't seem to find a simple method

<code>str.split(//)</code> does not seem to work like Ruby does. Is there a simple way of doing this without looping?
"
4990718|"Python: about catching ANY exception"|"How can I write a <code>try</code>/<code>except</code> block that catches all exceptions?
"
4998629|"Python: Split string with multiple delimiters"|"I found some answers online, but I have no experience with regular expressions, which I believe is what is needed here.

I have a string that needs to be split by either a ';' or ', '
That is, it has to be either a semicolon or a comma followed by a space. Individual commas without trailing spaces should be left untouched

Example string:

<code>""b-staged divinylsiloxane-bis-benzocyclobutene [124221-30-3], mesitylene [000108-67-8]; polymerized 1,2-dihydro-2,2,4- trimethyl quinoline [026780-96-1]""
</code>

should be split into a list containing the following:

<code>('b-staged divinylsiloxane-bis-benzocyclobutene [124221-30-3]' , 'mesitylene [000108-67-8]', 'polymerized 1,2-dihydro-2,2,4- trimethyl quinoline [026780-96-1]') 
</code>
"
5074225|"Python unexpected EOF while parsing"|"Here's my python code. Could someone show me what's wrong with it.

<code>while 1:
date=input(""Example: March 21 | What is the date? "")
if date==""June 21"":
    sd=""23.5° North Latitude""
if date==""March 21"" | date==""September 21"":
    sd=""0° Latitude""
if date==""December 21"":
    sd=""23.5° South Latitude""
if sd:
    print sd
</code>

And Here's what happens:

<code>&gt;&gt;&gt; 
Example: March 21 | What is the date? 
Traceback (most recent call last):
  File ""C:\Users\Daniel\Desktop\Solar Declination Calculater.py"", line 2, in &lt;module&gt;
    date=input(""Example: March 21 | What is the date? "")
  File ""&lt;string&gt;"", line 0

   ^
SyntaxError: unexpected EOF while parsing
&gt;&gt;&gt; 
</code>
"
5082452|"Python string formatting: % vs. .format"|"Python 2.6 introduced the <code>str.format()</code> method with a slightly different syntax from the existing <code>%</code> operator. Which is better and for what situations?


The following uses each method and has the same outcome, so what is the difference?

<code>#!/usr/bin/python
sub1 = ""python string!""
sub2 = ""an arg""

a = ""i am a %s"" % sub1
b = ""i am a {0}"".format(sub1)

c = ""with %(kwarg)s!"" % {'kwarg':sub2}
d = ""with {kwarg}!"".format(kwarg=sub2)

print a    # ""i am a python string!""
print b    # ""i am a python string!""
print c    # ""with an arg!""
print d    # ""with an arg!""
</code>
Furthermore when does string formatting occur in Python? For example, if my logging level is set to HIGH will I still take a hit for performing the following <code>%</code> operation? And if so, is there a way to avoid this?

<code>log.debug(""some debug info: %s"" % some_info)
</code>

"
5137497|"Find current directory and file's directory"|"In Python, what commands can I use to find:


the current directory (where I was in the terminal when I ran the Python script), and
where the file I am executing is?

"
5142418|"What is the use of ""assert"" in Python?"|"I have been reading some source code and in several places I have seen the usage of <code>assert</code>. 

What does it mean exactly? What is its usage?
"
5178292|"pip install mysql-python fails with EnvironmentError: mysql_config not found"|"This is the error I get

<code>(mysite)zjm1126@zjm1126-G41MT-S2:~/zjm_test/mysite$ pip install mysql-python
Downloading/unpacking mysql-python
  Downloading MySQL-python-1.2.3.tar.gz (70Kb): 70Kb downloaded
  Running setup.py egg_info for package mysql-python
    sh: mysql_config: not found
    Traceback (most recent call last):
      File ""&lt;string&gt;"", line 14, in &lt;module&gt;
      File ""/home/zjm1126/zjm_test/mysite/build/mysql-python/setup.py"", line 15, in &lt;module&gt;
        metadata, options = get_config()
      File ""setup_posix.py"", line 43, in get_config
        libs = mysql_config(""libs_r"")
      File ""setup_posix.py"", line 24, in mysql_config
        raise EnvironmentError(""%s not found"" % (mysql_config.path,))
    EnvironmentError: mysql_config not found
    Complete output from command python setup.py egg_info:
    sh: mysql_config: not found

Traceback (most recent call last):

  File ""&lt;string&gt;"", line 14, in &lt;module&gt;

  File ""/home/zjm1126/zjm_test/mysite/build/mysql-python/setup.py"", line 15, in &lt;module&gt;

    metadata, options = get_config()

  File ""setup_posix.py"", line 43, in get_config

    libs = mysql_config(""libs_r"")

  File ""setup_posix.py"", line 24, in mysql_config

    raise EnvironmentError(""%s not found"" % (mysql_config.path,))

EnvironmentError: mysql_config not found

----------------------------------------
Command python setup.py egg_info failed with error code 1
Storing complete log in /home/zjm1126/.pip/pip.log
(mysite)zjm1126@zjm1126-G41MT-S2:~/zjm_test/mysite$ pip install mysql-python
Downloading/unpacking mysql-python
  Running setup.py egg_info for package mysql-python
    sh: mysql_config: not found
    Traceback (most recent call last):
      File ""&lt;string&gt;"", line 14, in &lt;module&gt;
      File ""/home/zjm1126/zjm_test/mysite/build/mysql-python/setup.py"", line 15, in &lt;module&gt;
        metadata, options = get_config()
      File ""setup_posix.py"", line 43, in get_config
        libs = mysql_config(""libs_r"")
      File ""setup_posix.py"", line 24, in mysql_config
        raise EnvironmentError(""%s not found"" % (mysql_config.path,))
    EnvironmentError: mysql_config not found
    Complete output from command python setup.py egg_info:
    sh: mysql_config: not found

Traceback (most recent call last):

  File ""&lt;string&gt;"", line 14, in &lt;module&gt;

  File ""/home/zjm1126/zjm_test/mysite/build/mysql-python/setup.py"", line 15, in &lt;module&gt;

    metadata, options = get_config()

  File ""setup_posix.py"", line 43, in get_config

    libs = mysql_config(""libs_r"")

  File ""setup_posix.py"", line 24, in mysql_config

    raise EnvironmentError(""%s not found"" % (mysql_config.path,))

EnvironmentError: mysql_config not found

----------------------------------------
Command python setup.py egg_info failed with error code 1
Storing complete log in /home/zjm1126/.pip/pip.log
</code>

What can I do to resolve this?
"
5188792|"How to check a string for specific characters?"|"How can I check if a string value has exact characters in it using Python2?
Specifically, I am looking to detect if it has dollar signs (""$""), commas ("",""), and numbers.
"
5214578|"Python Print String To Text File"|"I'm using Python to open a text document:

<code>text_file = open(""Output.txt"", ""w"")

text_file.write(""Purchase Amount: "" 'TotalAmount')

text_file.close()
</code>

I want to enter the string called ""TotalAmount"" into the text document. Can someone please let me know how to do this?
"
5226311|"Installing specific package versions with pip"|"I'm trying to install version 1.2.2 of the MySQL_python adaptor, using a fresh virtualenv created with the <code>--no-site-packages</code> option. The current version shown in PyPi is 1.2.3. Is there a way to install the older version? I found an article stating that this should do it:

<code>pip install MySQL_python==1.2.2
</code>

When installed, however, it still shows MySQL_python-1.2.3-py2.6.egg-info in the site packages. Is this a problem specific to this package, or am I doing something wrong?
"
5319922|"Python - Check If Word Is In A String"|"I'm working with Python v2, and I'm trying to find out if you can tell if a word is in a string.

I have found some information about identifying if the word is in the string - using .find, but is there a way to do an IF statement. I would like to have something like the following:

<code>if string.find(word):
    print 'success'
</code>

Thanks for any help.
"
5404068|"How to read keyboard-input?"|"I would like to read data from the keyboard in python

I try this :

<code>nb = input('Choose a number')
print ('Number%s \n' % (nb))
</code>

and this one :

<code>conv = BufferedReader (InputStreamReader(System.inputStream))
nb = conv.readLine()
print ('Number %s \n' % (nb))
</code>

But nothing works, neither with eclipse nor in the terminal, it's always stop of the question. I can type a number but after nothing happen.

Do you know why?
"
5420789|"How to install psycopg2 with ""pip"" on Python?"|"I'm using <code>virtualenv</code> and I need to install ""psycopg2"".

I have done the following:

<code>pip install http://pypi.python.org/packages/source/p/psycopg2/psycopg2-2.4.tar.gz#md5=24f4368e2cfdc1a2b03282ddda814160
</code>

And I have the following messages:

<code>Downloading/unpacking http://pypi.python.org/packages/source/p/psycopg2/psycopg2
-2.4.tar.gz#md5=24f4368e2cfdc1a2b03282ddda814160
  Downloading psycopg2-2.4.tar.gz (607Kb): 607Kb downloaded
  Running setup.py egg_info for package from http://pypi.python.org/packages/sou
rce/p/psycopg2/psycopg2-2.4.tar.gz#md5=24f4368e2cfdc1a2b03282ddda814160
    Error: pg_config executable not found.

    Please add the directory containing pg_config to the PATH
    or specify the full executable path with the option:

        python setup.py build_ext --pg-config /path/to/pg_config build ...

    or with the pg_config option in 'setup.cfg'.
    Complete output from command python setup.py egg_info:
    running egg_info

creating pip-egg-info\psycopg2.egg-info

writing pip-egg-info\psycopg2.egg-info\PKG-INFO

writing top-level names to pip-egg-info\psycopg2.egg-info\top_level.txt

writing dependency_links to pip-egg-info\psycopg2.egg-info\dependency_links.txt

writing manifest file 'pip-egg-info\psycopg2.egg-info\SOURCES.txt'

warning: manifest_maker: standard file '-c' not found

Error: pg_config executable not found.



Please add the directory containing pg_config to the PATH

or specify the full executable path with the option:



    python setup.py build_ext --pg-config /path/to/pg_config build ...



or with the pg_config option in 'setup.cfg'.

----------------------------------------
Command python setup.py egg_info failed with error code 1
Storing complete log in C:\Documents and Settings\anlopes\Application Data\pip\p
ip.log
</code>

My question, I only need to do this to get the psycopg2 working?

<code>python setup.py build_ext --pg-config /path/to/pg_config build ...
</code>
"
5424716|"How to check if string input is a number?"|"How do I check if a user's string input is a number (e.g. <code>-1</code>, <code>0</code>, <code>1</code>, etc.)?

<code>user_input = input(""Enter something:"")

if type(user_input) == int:
    print(""Is a number"")
else:
    print(""Not a number"")
</code>

The above won't work since <code>input</code> always returns a string.
"
5458048|"How to make a Python script standalone executable to run without ANY dependency?"|"I'm building a Python application and don't want to force my clients to install Python and modules. I also want to make my application closed-source.

So, is there a way to compile Python scripts to standalone executables?
"
5471158|"TypeError: 'str' does not support the buffer interface"|"<code>plaintext = input(""Please enter the text you want to compress"")
filename = input(""Please enter the desired filename"")
with gzip.open(filename + "".gz"", ""wb"") as outfile:
    outfile.write(plaintext) 
</code>

The above python code is giving me following error:

<code>Traceback (most recent call last):
  File ""C:/Users/Ankur Gupta/Desktop/Python_works/gzip_work1.py"", line 33, in &lt;module&gt;
    compress_string()
  File ""C:/Users/Ankur Gupta/Desktop/Python_works/gzip_work1.py"", line 15, in compress_string
    outfile.write(plaintext)
  File ""C:\Python32\lib\gzip.py"", line 312, in write
    self.crc = zlib.crc32(data, self.crc) &amp; 0xffffffff
TypeError: 'str' does not support the buffer interface
</code>
"
5563089|"raw_input function in Python"|"What is the <code>raw_input</code> function? Is it a user interface? When do we use it?
"
5574702|"How to print to stderr in Python?"|"I've come across at least three ways to print to stderr:

<code> import sys

 print &gt;&gt; sys.stderr, 'spam'

 sys.stderr.write('spam\n')

 from __future__ import print_function
 print('spam', file=sys.stderr)
</code>

It seems to contradict zen of Python #13 †, so what's the preferred way to do it? Are there any advantages or disadvantages to one way or the other?

† There should be one — and preferably only one — obvious way to do it.
"
5584586|"Find the division remainder of a number"|"How could I go about finding the division remainder of a number in Python?

For example:
If the number is 26 and divided number is 7, then the division remainder is 5.
(since 7+7+7=21 and 26-21=5.)
"
5598181|"Python print on same line"|"I want to run a script, which basicly shows things like:

<code>Installing XXX...               [DONE]
</code>

Now, at the moment, I use print to print the whole line AFTER the function has succeeded. However, I now want it to print ""Installing xxx..."" first, and AFTER the function has run, to add the ""DONE"" tag; but on the same line.

Any ideas?
"
5607551|"How to urlencode a querystring in Python?"|"I am trying to urlencode this string before I submit. 

<code>queryString = 'eventName=' + evt.fields[""eventName""] + '&amp;' + 'eventDescription=' + evt.fields[""eventDescription""]; 
</code>
"
5653533|"IndexError: list assignment index out of range"|"Please consider the following code:

<code>i = [1, 2, 3, 5, 8, 13]
j = []
k = 0

for l in i:
    j[k] = l
    k += 1

print j
</code>

The output (Python 2.6.6 on Win 7 32-bit) is:

<code>&gt; Traceback (most recent call last): 
&gt;     j[k] = l IndexError: list assignment index out of range
</code>

I guess it's something simple I don't understand. Can someone clear it up?
"
5676646|"How can I fill out a Python string with spaces?"|"I want to fill out a string with spaces. I know that the following works for zero's:

<code>&gt;&gt;&gt; print  ""'%06d'""%4
'000004'
</code>

But what should I do when I want this?:

<code>'hi    '
</code>

of course I can measure string length and do <code>str+"" ""*leftover</code>, but I'd like the shortest way.
"
5685406|"""inconsistent use of tabs and spaces in indentation"""|"I'm trying to create an application in Python 3.2 and i use tabs all the time for indentation, but even the editor changes some of them into spaces and then print out ""inconsistent use of tabs and spaces in indentation"" when i try to run the program.

How can i change the spaces into tabs? It's driving me crazy. (I'm a beginner in programming). I would be glad if i could get some overall tips on my code, if i have done a lot of misstakes i would be happy to hear.

<code>import random

attraktioner = [""frittfall"",""bergodalbana"",""spökhuset""]


class Nojesfalt:
    def __init__(self, attraktion):
        self.val = attraktion
        self.langd = 0
        self.alder = 0


#längdgräns för fritt fall
    def langdgrans(self):
        print("""")
        self.langd = int(input(""Hur lång är du i cm? ""))
        if self.langd &lt; 140:
            print(""tyvärr, du är för kort, prova något annat"")
            return 0
        elif self.langd &gt;= 140:
            print(""håll dig hatten, nu åker vi!"")
            print("" "")
            return 1

#åldersgräns för spökhuset
    def aldersgrans(self):
        print("""")
        self.alder = int(input(""Hur gammal är du? ""))
        if self.alder &lt; 10:
            print(""tyvärr, du är för ung, prova något annat"")
            return 0
        elif self.alder &gt;= 10:
            print(""Gå in om du törs!"")
            print("" "")
            return 1


#åker attraktion frittfall lr bergodalbana
        def aka(self):
                print("""")
        print(self.val)
        tal = random.randint(0,100)
        if tal &lt; 20:
            print(""åkturen gick åt skogen, bättre lycka nästa gång"")            
        elif tal &gt;= 20:
            print(""jabbadabbbadoooooooo"")
            return 1

#går i spökhuset
        def aka1(self):
                print("""")
        print(self.val)
        tal = random.randint(0,100)
        if tal &lt; 20:
            print(""du är omringad av spöken och kan inte fortsätta"")            return 0
        elif tal &gt;= 20:
            print(""Buhuuuuuu, buuuhuuuu"")
            return 1

#programkod
print(""Välkommen till nöjesfältet, vad vill du göra?"")
print("" "")

while 1:
    vald_attr = input(""Vad vill du göra?\n1. frittfall\n2. bergodalbana\n3. spökhuset\n4. Avsluta\n"")
    if vald_attr == ""1"":
        val = Nojesfalt(attraktioner[0])
        if val.langdgrans() == 1:
            val.aka()
    elif vald_attr == ""2"":
        val = Nojesfalt(attraktioner[1])
        val.aka()
    elif vald_attr == ""3"":
        val = Nojesfalt(attraktioner[2])
        if val.aldersgrans() == 1:
            val.aka1()
    elif vald_attr == ""4"":
        break
</code>
"
5844672|"Delete an item from a dictionary"|"Is there a way to delete an item from a dictionary in Python?

I know I can just call <code>.pop</code> on the dictionary, but that returns the item that was removed. What I'm looking for is something returns the dictionary minus the element in question. 

At present I have a helper function that accepts the dictionary in question as parameter, and then returns a dictionary with the item removed, Is there a more elegant solution?
"
5904969|"How to print a dictionary's key?"|"I found a my question in SO already, but it was not answered directly. I would like to print a specific Python dictionary key:

<code>mydic = {}
mydic['key_name'] = 'value_name'
</code>

Now I can check if <code>mydic.has_key('key_name')</code>, but what I would like to do is print the name of the key <code>'key_name'</code>. Of course I could use <code>mydic.items()</code>, but I don't want all the keys listed, merely one specific key. For instance I'd expect something like this (in pseudo-code):

<code>print ""the key name is"", mydic['key_name'].name_the_key(), ""and its value is"", mydic['key_name']
</code>

Is there any <code>name_the_key()</code> method to print a key name?



Edit:
OK, thanks a lot guys for your reactions! :) I realise my question is not well formulated and trivial. I just got confused because i realised key_name and <code>mydic['key_name']</code> are two different things and i thought it would incorrect to print the <code>key_name</code> out of the dictionary context. But indeed i can simply use the 'key_name' to refer to the key! :)
"
5971312|"How to set environment variables in Python"|"I need to set some environment variables in the python script and I want all the other scripts that are called from python (shell scripts) which will be child process to see the environment variables set. The value is a number.

If I do <code>os.environ[""DEBUSSY""] = 1</code>, it complains saying that <code>1</code> has to be string.
I also want to know how to read the environment variables in python (in the later part of the script) once I set it. 
"
5982206|"How to print a linebreak in a python function?"|"I have a list of strings in my code;

<code>A = ['a1', 'a2', 'a3' ...]
B = ['b1', 'b2', 'b3' ...]
</code>

and I want to print them separated by a linebreak, like this:

<code>&gt;a1
b1
&gt;a2
b2
&gt;a3
b3
</code>

I've tried:

<code>print '&gt;' + A + '/n' + B
</code>

But /n isn't recognized like a line break.
"
5998245|"Get current time in milliseconds in Python?"|"How can I get the current time in milliseconds in Python? 
"
6039605|"TypeError: 'str' object is not callable (Python)"|"Code:

<code>import urllib2 as u
import os as o
inn = 'dword.txt'
w = open(inn)
z = w.readline()
b = w.readline()
c = w.readline()
x = w.readline()
m = w.readline()
def Dict(Let, Mod):
    global str
    inn = 'dword.txt'
    den = 'definitions.txt'

    print 'reading definitions...'

    dell =open(den, 'w')

    print 'getting source code...'
    f = u.urlopen('http://dictionary.reference.com/browse/' + Let)
    a = f.read(800)

    print 'writing source code to file...'
    f = open(""dic1.txt"", ""w"")
    f.write(a)
    f.close()

    j = open('defs.txt', 'w')

    print 'finding definition is source code'
    for line in open(""dic1.txt""):
        if '&lt;meta name=""description"" content=' in line:
           j.write(line)

    j.close()

    te = open('defs.txt', 'r').read().split()
    sto = open('remove.txt', 'r').read().split()

    print 'skimming down the definition...'
    mar = []
    for t in te:
        if t.lower() in sto:
            mar.append('')
        else: 
            mar.append(t)
    print mar
    str = str(mar)
    str = ''.join([ c for c in str if c not in ("","", ""'"", '[', ']', '')])

    defin = open(den, Mod)
    defin.write(str)
    defin.write('                 ')
    defin.close()

    print 'cleaning up...'
    o.system('del dic1.txt')
    o.system('del defs.txt')
Dict(z, 'w')
Dict(b, 'a')
Dict(c, 'a')
Dict(x, 'a')
Dict(m, 'a')
print 'all of the definitions are in definitions.txt'
</code>

The first <code>Dict(z, 'w')</code> works and then the second time around it comes up with an error:

<code>Traceback (most recent call last):
  File ""C:\Users\test.py"", line 64, in &lt;module&gt;
    Dict(b, 'a')
  File ""C:\Users\test.py"", line 52, in Dict
    str = str(mar)
TypeError: 'str' object is not callable
</code>

Does anyone know why this is?

@Greg Hewgill: 

I've already tried that and I get the error:

<code>Traceback (most recent call last):
 File ""C:\Users\test.py"", line 63, in &lt;module&gt;
    Dict(z, 'w')
  File ""C:\Users\test.py"", line 53, in Dict
   strr = ''.join([ c for c in str if c not in ("","", ""'"", '[', ']', '')])
TypeError: 'type' object is not iterable
</code>
"
6049933|"django import error - No module named core.management"|"Ok, I see plenty of these errors around. I have tried everything I know to do and have yet to figure this out.

I am working on a development server running python 2.5 and Django 1.3. Django 1.3 was installed using python setup.py install after unpacking the tar.gz download.

All works well, I seldom have the need to run <code>manage.py</code> but am trying to use the new staticfiles app and am running into problems.

<code>python manage.py collectstatic
Traceback (most recent call last):
  File ""manage.py"", line 2, in &lt;module&gt;
    from django.core.management import execute_manager
ImportError: No module named core.management
</code>

Ok, so I have <code>PATH</code> issue.

From Django install I double check my <code>site-packages</code> directory.

<code>python -c ""from distutils.sysconfig import get_python_lib; print get_python_lib()""
/usr/lib/python2.5/site-packages
</code>

Ok, let's check out what I have, echo $PYTHON_PATH was empty, so I set it

<code>export PYTHON_PATH=/usr/lib/python2.5/site-packages/django
</code>

Still no luck. Lets check what sys.path has to say

<code>&gt;&gt;&gt; import sys
&gt;&gt;&gt; print sys.path
['', '/usr/lib/python2.5', '/usr/lib/python2.5/plat-linux2', '/usr/lib/python2.5/lib-tk', '/usr/lib/python2.5/lib-dynload', '/usr/local/lib/python2.5/site-packages', '/usr/lib/python2.5/site-packages', '/usr/lib/python2.5/site-packages/PIL', '/usr/lib/python2.5/site-packages/django', '/var/lib/python-support/python2.5']
</code>

path is there, I even created /usr/lib/python2.5/site-packages/django.pth with contents

<code>cat /usr/lib/python2.5/site-packages/django.pth 
/usr/lib/python2.5/site-packages/django/
</code>

Anyone got an clues to what is going on here? 

I found a symlink further up the path that was getting in the way, but no on to a new error.

<code>python manage.py collectstatic
Traceback (most recent call last):
  File ""manage.py"", line 14, in &lt;module&gt;
    execute_manager(settings)
  File ""/usr/lib/python2.5/site-packages/django/core/management/__init__.py"", line 438, in execute_manager
    utility.execute()
  File ""/usr/lib/python2.5/site-packages/django/core/management/__init__.py"", line 349, in execute
    version=get_version(),
  File ""/usr/lib/python2.5/site-packages/django/__init__.py"", line 12, in get_version
    from django.utils.version import get_svn_revision
ImportError: No module named utils.version
</code>

I also tried creating a new project to see if there were any issues there and get the same utils.version error.

Side node: Unode from #django helped me a bit, set up virtualenv on same machine and got past the errors so still not sure what is up with this actual install here, but it seems to not be in the django projects but in the django/python install.
"
6077675|"Why am I seeing ""TypeError: string indices must be integers""?"|"I'm playing with both learning python and trying to get github issues into a readable form. Using the advice on How can I convert JSON to CSV? I came up with this:

<code>import json
import csv

f=open('issues.json')
data = json.load(f)
f.close()

f=open(""issues.csv"",""wb+"")
csv_file=csv.writer(f)

csv_file.writerow([""gravatar_id"",""position"",""number"",""votes"",""created_at"",""comments"",""body"",""title"",""updated_at"",""html_url"",""user"",""labels"",""state""])

for item in data:
        csv_file.writerow([item[""gravatar_id""], item[""position""], item[""number""], item[""votes""], item[""created_at""], item[""comments""], item[""body""], item[""title""], item[""updated_at""], item[""html_url""], item[""user""], item[""labels""], item[""state""]])
</code>

Where ""issues.json"" is the json file containing my github issues. When I try to run that, I get 

<code>File ""foo.py"", line 14, in &lt;module&gt;
csv_file.writerow([item[""gravatar_id""], item[""position""], item[""number""], item[""votes""], item[""created_at""], item[""comments""], item[""body""], item[""title""], item[""updated_at""], item[""html_url""], item[""user""], item[""labels""], item[""state""]])

TypeError: string indices must be integers
</code>

What am I missing here? Which are the ""string indices""? I'm sure that once I get this working I'll have more issues, but for now , I'd just love for this to work!

UPDATE: 
When I tweak the <code>for</code> statement to simply 

<code>for item in data:
    print item
</code>

what I get is ... ""issues"" -- so I'm doing something more basic wrong. Here's a bit of my json:

<code>{""issues"":[{""gravatar_id"":""44230311a3dcd684b6c5f81bf2ec9f60"",""position"":2.0,""number"":263,""votes"":0,""created_at"":""2010/09/17 16:06:50 -0700"",""comments"":11,""body"":""Add missing paging (Older&gt;&gt;) links...
</code>

when I print <code>data</code> it looks like it is getting munged really oddly:

<code>{u'issues': [{u'body': u'Add missing paging (Older&gt;&gt;) lin...
</code>
"
6159900|"Correct way to write line to file in Python"|"I'm used to doing <code>print &gt;&gt;f, ""hi there""</code>

However, it seems that <code>print &gt;&gt;</code> is getting deprecated. What is the recommended way to do the line above?

Update:
Regarding all those answers with <code>""\n""</code>...is this universal or Unix-specific? IE, should I be doing <code>""\r\n""</code> on Windows?
"
6318156|"Adding Python Path on Windows 7"|"I've been trying to add the Python path to the command line on Windows 7, yet no matter the method I try, nothing seems to work. I've used the <code>set</code> command, I've tried adding it through the Edit Environment variables prompt etc.

Further more if I run the set command on the command line it lists this

<code>python = c:\python27
</code>

Yet it still doesn't recognize the Python command.

Reading the documentation, and various other sources hasn't seemed to help.

Edit: Just to clarify further, I've appended the path of the Python executable to PATH in edit environment prompt. Doesn't seem to work.
"
6390393|"Matplotlib make tick labels font size smaller"|"In a matplotlib figure, how can I make the font size for the tick labels using <code>ax1.set_xticklabels()</code> smaller?

Further, how can one rotate it from horizontal to vertical?
"
6416131|"Python add new item to dictionary"|"I want to add an item to an existing dictionary in python. For example, this is my dictionary:

<code>default_data = {
            'item1': 1,
            'item2': 2,
}
</code>

I want to add new item such that:

<code>default_data = default_data + {'item3':3}
</code>

How to achieve this?
"
6468397|"How to check Django version"|"I have to use Python and Django for our application. So I have two versions of Python, 2.6 and 2.7. Now I have installed Django. I could run the sample application for testing Django succesfuly. But how do I make sure whether Django uses the 2.6 or 2.7 version and what version of modules Django uses?
"
6470428|"Catch multiple exceptions in one line (except block)"|"I know that I can do:

<code>try:
    # do something that may fail
except:
    # do this if ANYTHING goes wrong
</code>

I can also do this:

<code>try:
    # do something that may fail
except IDontLikeYouException:
    # say please
except YouAreTooShortException:
    # stand on a ladder
</code>

But if I want to do the same thing inside two different exceptions, the best I can think of right now is to do this:

<code>try:
    # do something that may fail
except IDontLikeYouException:
    # say please
except YouAreBeingMeanException:
    # say please
</code>

Is there any way that I can do something like this (since the action to take in both exceptions is to <code>say please</code>):

<code>try:
    # do something that may fail
except IDontLikeYouException, YouAreBeingMeanException:
    # say please
</code>

Now this really won't work, as it matches the syntax for:

<code>try:
    # do something that may fail
except Exception, e:
    # say please
</code>

So, my effort to catch the two distinct exceptions doesn't exactly come through.

Is there a way to do this?
"
6504810|"How to install lxml on Ubuntu"|"I'm having difficulty installing lxml with easy_install on Ubuntu 11.

When I type <code>$ easy_install lxml</code> I get:

<code>Searching for lxml
Reading http://pypi.python.org/simple/lxml/
Reading http://codespeak.net/lxml
Best match: lxml 2.3
Downloading http://lxml.de/files/lxml-2.3.tgz
Processing lxml-2.3.tgz
Running lxml-2.3/setup.py -q bdist_egg --dist-dir /tmp/easy_install-7UdQOZ/lxml-2.3/egg-dist-tmp-GacQGy
Building lxml version 2.3.
Building without Cython.
ERROR: /bin/sh: xslt-config: not found

** make sure the development packages of libxml2 and libxslt are installed **

Using build configuration of libxslt 
In file included from src/lxml/lxml.etree.c:227:0:
src/lxml/etree_defs.h:9:31: fatal error: libxml/xmlversion.h: No such file or directory
compilation terminated.
</code>

It seems that <code>libxslt</code> or <code>libxml2</code> is not installed. I've tried following the instructions at http://www.techsww.com/tutorials/libraries/libxslt/installation/installing_libxslt_on_ubuntu_linux.php and http://www.techsww.com/tutorials/libraries/libxml/installation/installing_libxml_on_ubuntu_linux.php with no success.

If I try <code>wget ftp://xmlsoft.org/libxml2/libxml2-sources-2.6.27.tar.gz</code> I get

<code>&lt;successful connection info&gt;
==&gt; SYST ... done.    ==&gt; PWD ... done.
==&gt; TYPE I ... done.  ==&gt; CWD (1) /libxml2 ... done.
==&gt; SIZE libxml2-sources-2.6.27.tar.gz ... done.
==&gt; PASV ... done.    ==&gt; RETR libxml2-sources-2.6.27.tar.gz ... 
No such file `libxml2-sources-2.6.27.tar.gz'.
</code>

If I try the other first, I'll get to <code>./configure --prefix=/usr/local/libxslt --with-libxml-prefix=/usr/local/libxml2</code> and that will fail eventually with:

<code>checking for libxml libraries &gt;= 2.6.27... configure: error: Could not find libxml2 anywhere, check ftp://xmlsoft.org/.
</code>

I've tried both versions <code>2.6.27</code> and <code>2.6.29</code> of <code>libxml2</code> with no difference.

Leaving no stone unturned, I have successfully done <code>sudo apt-get install libxml2-dev</code>, but this changes nothing.
"
6587507|"How to install pip with Python 3?"|"I want to install pip. It should support Python 3, but it requires setuptools, which is available only for Python 2.

How can I install pip with Python 3?
"
6591931|"Getting file size in Python?"|"Is there a built-in function for getting the size of a file object in bytes? I see some people do something like this:

<code>def getSize(fileobject):
    fileobject.seek(0,2) # move the cursor to the end of the file
    size = fileobject.tell()
    return size

file = open('myfile.bin', 'rb')
print getSize(file)
</code>

But from my experience with Python, it has a lot of helper functions so I'm guessing maybe there is one built-in.
"
6600878|"Find all packages installed with easy_install/pip?"|"Is there a way to find all Python PyPI packages that were installed with easy_install or pip?  I mean, excluding everything that was/is installed with the distributions tools (in this case apt-get on Debian).
"
6618002|"Python @property versus getters and setters"|"Here is a pure Python-specific design question: 

<code>class MyClass(object):
    ...
    def get_my_attr(self):
        ...

    def set_my_attr(self, value):
        ...
</code>

and 

<code>class MyClass(object):
    ...        
    @property
    def my_attr(self):
        ...

    @my_attr.setter
    def my_attr(self, value):
        ...
</code>

Python lets us to do it either way. If you would design a Python program, which approach would you use and why?
"
6667201|"How to define two-dimensional array in python"|"I want to define a two-dimensional array without an initialized length like this :

<code>Matrix = [][]
</code>

but it does not work...

I've tried the code below, but it is wrong too:

<code>Matrix = [5][5]
</code>

Error:

<code>Traceback ...

IndexError: list index out of range
</code>

What is my mistake?
"
6797984|"How to convert string to lowercase in Python?"|"Is there any way to convert an entire user inputted string from uppercase, or even part uppercase to lowercase? 

E.g. Kilometers --> kilometers.
"
6996603|"How to delete a file or folder?"|"How do I delete a file or folder in Python?
"
7129285|"Why would you use the return statement in Python?"|"What is the simple basic explanation of what the return statement is, how to use it in Python?

And what is the difference between it and the <code>print</code> statement?
"
7152762|"How to redirect 'print' output to a file using python?"|"I want to redirect the print to a .txt file using python. I have a 'for' loop, which will 'print' the output for each of my .bam file; while I want to redirect ALL these output to one file. So I tried to put

<code> f = open('output.txt','w'); sys.stdout = f
</code>

at the beginning of my script. However I get nothing in the .txt file.
My script is like below:

<code>#!/usr/bin/python

import os,sys
import subprocess
import glob
from os import path

f = open('output.txt','w')
sys.stdout = f

path= '/home/xug/nearline/bamfiles'
bamfiles = glob.glob(path + '/*.bam')

for bamfile in bamfiles:
    filename = bamfile.split('/')[-1]
    print 'Filename:', filename
    samtoolsin = subprocess.Popen([""/share/bin/samtools/samtools"",""view"",bamfile],
                                  stdout=subprocess.PIPE,bufsize=1)
    linelist= samtoolsin.stdout.readlines()
    print 'Readlines finished!'
    ........print....
    ........print....
</code>

So what's the problem? Any other way besides this sys.stdout?
thx

edit:
and i need my result look like:

<code>Filename: ERR001268.bam
Readlines finished!
Mean: 233
SD: 10
Interval is: (213, 252)
</code>
"
7225900|"How to pip install packages according to requirements.txt from a local directory?"|"Here is the problem

I have a requirements.txt that looks like:

<code>BeautifulSoup==3.2.0
Django==1.3
Fabric==1.2.0
Jinja2==2.5.5
PyYAML==3.09
Pygments==1.4
SQLAlchemy==0.7.1
South==0.7.3
amqplib==0.6.1
anyjson==0.3
...
</code>

I have a local archive directory containing all the packages + others.

I have created a new virtualenv with

<code>bin/virtualenv testing
</code>

upon activating it, I tried to install the packages according to requirements.txt from the local archive directory.

<code>source bin/activate
pip install -r /path/to/requirements.txt -f file:///path/to/archive/
</code>

I got some output that seems to indicate that the installation is fine

<code>Downloading/unpacking Fabric==1.2.0 (from -r ../testing/requirements.txt (line 3))
  Running setup.py egg_info for package Fabric
    warning: no previously-included files matching '*' found under directory 'docs/_build'
    warning: no files found matching 'fabfile.py'
Downloading/unpacking South==0.7.3 (from -r ../testing/requirements.txt (line 8))
  Running setup.py egg_info for package South
....
</code>

But later check revealed none of the package is installed properly. I cannot import the package, and none is found in the site-packages directory of my virtualenv. So what went wrong?
"
7263824|"Get HTML Source of WebElement in Selenium WebDriver using Python"|"I'm using the Python bindings to run Selenium WebDriver.

<code>from selenium import webdriver
wd = webdriver.Firefox()
</code>

I know I can grab a webelement like so...

<code>elem = wd.find_element_by_css_selector('#my-id')
</code>

And I know I can get the full page source with...

<code>wd.page_source
</code>

But is there anyway to get the ""element source""?

<code>elem.source   # &lt;-- returns the HTML as a string
</code>

The selenium webdriver docs for Python are basically non-existent and I don't see anything in the code that seems to enable that functionality.

Any thoughts on the best way to access the HTML of an element (and its children)?
"
7370801|"Measure time elapsed in Python?"|"What I want is to start counting time somewhere in my code and then get the passed time, to measure the time it took to execute few function. I think I'm using the timeit module wrong, but the docs are just confusing for me.

<code>import timeit

start = timeit.timeit()
print ""hello""
end = timeit.timeit()
print end - start
</code>
"
7446187|"No module named pkg_resources"|"I'm deploying a Django app to a dev server and am hitting this error when i run pip install requirements.txt:

<code>Traceback (most recent call last):
  File ""/var/www/mydir/virtualenvs/dev/bin/pip"", line 5, in &lt;module&gt;
    from pkg_resources import load_entry_point
ImportError: No module named pkg_resources
</code>

pkg_resources appears to be distributed with setuptools.  Initially I thought this might not be installed to the python in the virtualenv so I installed setuptools (2.6, same version as Python) to the Python site-packages in the virtualenv with the following command

<code>sh setuptools-0.6c11-py2.6.egg --install-dir /var/www/mydir/virtualenvs/dev/lib/python2.6/site-packages
</code>

EDIT
This only happens inside the virtualenv.  If I open a console outside the virtualenv then pkg_resources is present

but I am still getting the same error.  Any ideas as to why pkg_resources is not on the path?
"
7475223|"mysql_config not found when installing mysqldb python interface"|"I am trying to get a Python script to run on the linux server I'm connected to via ssh. The script uses mysqldb. I have all the other components I need, but when I try to install mySQLdb via setuptools like so:, 

<code>python setup.py install
</code>

I get the following error report related to the <code>mysql_config</code> command.

<code>sh: mysql_config: command not found
Traceback (most recent call last):
  File ""setup.py"", line 15, in &lt;module&gt;
    metadata, options = get_config()
  File ""/usr/lib/python2.5/MySQL-python-1.2.3/setup_posix.py"", line 43, in get_config
    libs = mysql_config(""libs_r"")
  File ""/usr/lib/python2.5/MySQL-python-1.2.3/setup_posix.py"", line 24, in mysql_config
    raise EnvironmentError(""%s not found"" % (mysql_config.path,))
EnvironmentError: mysql_config not found
</code>

Has anyone else encountered this error and if so how did you resolve it/what can I do to successfully install mysqldb? 
"
7571635|"Fastest way to check if a value exist in a list"|"I'm searching for the fastest way to know if a value exists in a list (a list with millions of values in it) and what its index is? I know all values in the list are unique like my example.

My first methods I try is(3.8sec in my real code):

<code>a = [4,2,3,1,5,6]

if a.count(7) == 1:
    b=a.index(7)
    ""Do something with variable b""
</code>

My second methods I try is (2x faster:1.9sec on my real code):

<code>a = [4,2,3,1,5,6]

try:
    b=a.index(7)
except ValueError:
    ""Do nothing""
else:
    ""Do something with variable b""
</code>

Proposed methods from Stackoverflow user (2.74sec on my real code):

<code>a = [4,2,3,1,5,6]
if 7 in a:
    a.index(7)
</code>

In my real code, first method take 3.81sec and the second methods take 1.88sec.
It's a good improvement but:

I'm a beginner with Python/scripting and I want to know if a fastest way exist to do the same things and save more process time?

More specific explication for my application:

In the API of blender a can access to a list of particles:

<code>particles = [1,2,3,4...etc.]
</code>

From there , I can access to it's location:

<code>particles[x].location = [x,y,z]
</code>

And I test for each particles if a neighbour exist by searching
in the location of each particles like:

<code>if [x+1,y,z] in particles.location
    ""find the identity of this neighbour particles in x:the index 
    of the particles array""
    particles.index([x+1,y,z])
</code>
"
7585435|"Best way to convert string to bytes in Python 3?"|"There appears to be two different ways to convert a string to bytes, as seen in the answers to TypeError: &#39;str&#39; does not support the buffer interface

Which of these methods would be better or more Pythonic? Or is it just a matter of personal preference?

<code>b = bytes(mystring, 'utf-8')

b = mystring.encode('utf-8')
</code>
"
7586063|"How to calculate the angle between a line and the horizontal axis?"|"In a programming language (Python, C#, etc) I need to determine how to calculate the angle between a line and the horizontal axis?

I think an image describes best what I want:



Given (P1x,P1y) and (P2x,P2y) what is the best way to calculate this angle? The origin is in the topleft and only the positive quadrant is used.
"
7604966|"Maximum and Minimum values for ints"|"I am looking for minimum and maximum values for integers in python. For eg., in Java, we have <code>Integer.MIN_VALUE</code> and <code>Integer.MAX_VALUE</code>. Is there something like this in python?
"
7696924|"Way to create multiline comments in Python?"|"I have recently started studying Python, but I couldn't find how to implement multi-line comments. Most languages have block comment symbols like 

<code>/* 

*/
</code>

I tried this in Python, but it throws an error, so this probably is not the correct way. Does Python actually have a multiline comment feature?
"
7716331|"Calculating arithmetic mean (average) in Python"|"Is there a built-in or standard library method in Python to calculate the arithmetic mean (average) of a list of numbers?
"
7771011|"Parse JSON in Python"|"My project is currently receiving a JSON message in python which I need to get bits of information out of. For the purposes of this, lets set it to some simple JSON in a string:

<code>jsonStr = '{""one"" : ""1"", ""two"" : ""2"", ""three"" : ""3""}'
</code>

So far I've been generating JSON requests using a list and then <code>json.dumps</code> but to do the opposite of this I think I need to use <code>json.loads</code> but I haven't had much luck with it. Could anyone provide me a snippet that would return ""2"" with the input of ""two"" in the above example?
"
7818811|"Import Error: No module named numpy"|"I have a very similar question to this question, but still 1 step behind. 
I have only one version of python 3 installed on my Windows 7(sorry) 64-bit system.
I installed numpy following this link - as suggested in the question. 
The installation went fine but when I want to import

<code>import numpy

Import error:No module named numpy
</code>

I know this is probably a super basic question, but I'm still learning...
Thanks
"
7899732|"Which is the best IDE for Python For Windows"|"
  Possible Duplicate:
  What IDE to use for Python?  




I am new to python and I am using simple gedit application on linux machine to write python code, however its very difficult to manage the indentations of my code. I am looking for any Python IDEs that provides some functionality and should not slow down my P4 machine.
"
7961363|"Removing duplicates in lists"|"Pretty much I need to write a program to check if a list has any duplicates and if it does it removes them and returns a new list with the items that werent duplicated/removed. This is what I have but to be honest I do not know what to do.

<code>def remove_duplicates():
    t = ['a', 'b', 'c', 'd']
    t2 = ['a', 'c', 'd']
    for t in t2:
        t.append(t.remove())
    return t
</code>
"
7999935|"Python datetime to string without microsecond component"|"I'm adding UTC time strings to Bitbucket API responses that currently only contain Amsterdam (!) time strings. For consistency with the UTC time strings returned elsewhere, the desired format is <code>2011-11-03 11:07:04</code> (followed by <code>+00:00</code>, but that's not germane).

What's the best way to create such a string (without a microsecond component) from a <code>datetime</code> instance with a microsecond component?

<code>&gt;&gt;&gt; import datetime
&gt;&gt;&gt; print unicode(datetime.datetime.now())
2011-11-03 11:13:39.278026
</code>

I'll add the best option that's occurred to me as a possible answer, but there may well be a more elegant solution.

Edit: I should mention that I'm not actually printing the current time – I used <code>datetime.now</code> to provide a quick example. So the solution should not assume that any <code>datetime</code> instances it receives will include microsecond components.
"
8009882|"How to read large file, line by line in python"|"I want to iterate over each line of an entire file. One way to do this is by reading the entire file, saving it to a list, then going over the line of interest. This method uses a lot of memory, so I am looking for an alternative.

My code so far:

<code>for each_line in fileinput.input(input_file):
    do_something(each_line)

    for each_line_again in fileinput.input(input_file):
        do_something(each_line_again)
</code>

Executing this code gives an error message: <code>device active</code>.

Any suggestions?

EDIT: The purpose is to calculate pair-wise string similarity, meaning for each line in file, I want to calculate the Levenshtein distance with every other line.
"
8023306|"Get key by value in dictionary"|"I made a function which will look up ages in dictionary and show the matching name:

<code>list = {'george':16,'amber':19}
search_age = raw_input(""Provide age"")
for age in list.values():
    if age == search_age:
        name = list[age]
        print name
</code>

I know how to compare and find the age I just don't know how to show the name of the person. Additionally, I am getting a <code>KeyError</code> because of line 5. I know it's not correct but I can't figure out to make it search backwards.
"
8113782|"Split string on whitespace in Python"|"I'm looking for the Python equivalent of 

<code>String str = ""many   fancy word \nhello    \thi"";
String whiteSpaceRegex = ""\\s"";
String[] words = str.split(whiteSpaceRegex);

[""many"", ""fancy"", ""word"", ""hello"", ""hi""]
</code>
"
8214932|"How to check if a value exists in a dictionary (python)"|"I have the following dictionary in python: 

<code>d = {'1': 'one', '3': 'three', '2': 'two', '5': 'five', '4': 'four'}
</code>

I need a way to find if a value such as ""one"" or ""two"" exists in this dictionary.

For example, if I wanted to know if the index ""1"" existed I would simply have to type: 

<code>""1"" in d
</code>

And then python would tell me if that is true or false, however I need to do that same exact thing except to find if a value exists.
"
8237647|"Clear variable in python"|"Is there a way to clear the value of a variable in python?

For example if I was implementing a binary tree:

<code>Class Node:
    self.left = somenode1
    self.right = somenode2
</code>

If I wanted to remove some node from the tree, I would need to set <code>self.left</code> to empty.
"
8248397|"How to know/change current directory in Python shell?"|"I am using Python 3.2 on Windows 7.  When I open the Python shell, how can I know what the current directory is and how can I change it to another directory where my modules are?
"
8266529|"Python - convert string to list"|"
  Possible Duplicate:
  String to list in Python  




i have a string like this :


  states = ""Alaska Alabama Arkansas American Samoa Arizona California Colorado""


and I want to split it into a list like this


  states = {Alaska, Alabama, Arkansas, American, Samoa, ....}


I am new in python.

Help me please. :-))

edit: I need to make random choice from states and make it like variable .
"
8270092|"Python remove all whitespace in a string"|"I want to eliminate all the whitespace from a string, on both ends, and in between words.

I have this Python code:

<code>def my_handle(self):
    sentence = ' hello  apple  '
    sentence.strip()
</code>

But that only eliminates the whitespace on both sides of the string. How do I remove all whitespace?
"
8369219|"How do I read a text file into a string variable in Python"|"I use the following code segment to read a file in python

<code>with open (""data.txt"", ""r"") as myfile:
    data=myfile.readlines()
</code>

input file is

<code>LLKKKKKKKKMMMMMMMMNNNNNNNNNNNNN
GGGGGGGGGHHHHHHHHHHHHHHHHHHHHEEEEEEEE
</code>

and when I print data I get

<code>['LLKKKKKKKKMMMMMMMMNNNNNNNNNNNNN\n', 'GGGGGGGGGHHHHHHHHHHHHHHHHHHHHEEEEEEEE']
</code>

As I see data is in list form. How do I make it string. And also how do I remove ""\n"", ""["", and ""]"" characters from it ?
"
8384737|"Extract file name from path, no matter what the os/path format"|"Which Python library can I use to extract filenames from paths, no matter what the operating system or path format could be?

For example, I'd like all of these paths to return me <code>c</code>:

<code>a/b/c/
a/b/c
\a\b\c
\a\b\c\
a\b\c
a/b/../../a/b/c/
a/b/../../a/b/c
</code>
"
8424942|"Creating a new dict in Python"|"I want to build a dictionary in Python. However, all the examples that I see are instantiating a dictionary from a list, etc . ..

How do I create a new empty dictionary in Python?
"
8551735|"How do I run Python code from Sublime Text 2?"|"I want to set up a complete Python IDE in Sublime Text 2.

I want to know how to run the Python code from within the editor. Is it done using build system? How do I do it ?
"
8777753|"Converting datetime.date to UTC timestamp in Python"|"I am dealing with dates in Python and I need to convert them to UTC timestamps to be used
inside Javascript. The following code does not work:

<code>&gt;&gt;&gt; d = datetime.date(2011,01,01)
&gt;&gt;&gt; datetime.datetime.utcfromtimestamp(time.mktime(d.timetuple()))
datetime.datetime(2010, 12, 31, 23, 0)
</code>

Converting the date object first to datetime also does not help. I tried the example at this link from, but:

<code>from pytz import utc, timezone
from datetime import datetime
from time import mktime
input_date = datetime(year=2011, month=1, day=15)
</code>

and now either:

<code>mktime(utc.localize(input_date).utctimetuple())
</code>

or

<code>mktime(timezone('US/Eastern').localize(input_date).utctimetuple())
</code>

does work.

So general question: how can I get a date converted to seconds since epoch according to UTC?
"
8858008|"How to move a file in Python"|"I looked into the Python <code>os</code> interface, but was unable to locate a method to move a file. How would I do the equivalent of <code>$ mv ...</code> in Python?

<code>&gt;&gt;&gt; source_files = '/PATH/TO/FOLDER/*'
&gt;&gt;&gt; destination_folder = 'PATH/TO/FOLDER'
&gt;&gt;&gt; # equivalent of $ mv source_files destination_folder
</code>
"
8885663|"How to format a floating number to fixed width in Python"|"How do I format a floating number to a fixed width with the following requirements:


Leading zero if n &lt; 1
Add trailing decimal zero(s) to fill up fixed width
Truncate decimal digits past fixed width
Align all decimal points


For example:

<code>% formatter something like '{:06}'
numbers = [23.23, 0.123334987, 1, 4.223, 9887.2]

for number in numbers:
    print formatter.format(number)
</code>

The output would be like

<code>  23.2300
   0.1233
   1.0000
   4.2230
9887.2000
</code>
"
8917885|"Which version of Python do I have installed?"|"I have to run a Python script on a Windows server. How can I know which version of Python I have, and does it even really matter? I was thinking of updating to latest version of Python.
"
8930915|"Append dictionary to a dictionary?"|"I have two existing dictionaries, and I wish to 'append' one of them to the other. By that I mean that the key,values of the other dictionary should be made into the first dictionary. For example:

<code>orig = {
   'A': 1,
   'B': 2,
   'C': 3,
}

extra = {
   'D': 4,
   'E': 5,
}

dest = # something here involving orig and extra

print dest
{
   'A': 1,
   'B': 2,
   'C': 3,
   'D': 4,
   'E': 5
}
</code>

I think this all can be achieved through a <code>for</code> loop (maybe?), but is there some method of dictionaries or any other module that saves this job for me? The actual dictionaries I'm using are really big...
"
8933237|"How to find if directory exists in Python"|"In the <code>os</code> module in Python, is there a way to find if a directory exists, something like:

<code>&gt;&gt;&gt; os.direxists(os.path.join(os.getcwd()), 'new_folder')) # in pseudocode
True/False
</code>
"
8949252|"Python: Attribute Error - 'NoneType' object has no attribute 'something'"|"I keep getting an error that says

<code>AttributeError: 'NoneType' object has no attribute 'something'
</code>

The code I have is too long to post here, but I was wondering if someone could give a gist of what general scenarios would be cause this 'AttributeError', and what 'NoneType' is supposed to mean? (Usually you would receive the name of some object where the code went wrong, but since it gives me 'NoneType' I'm not sure how it's possible to narrow down what's going on, other than line #)
"
9001509|"How can I sort a dictionary by key?"|"What would be a nice way to go from <code>{2:3, 1:89, 4:5, 3:0}</code> to <code>{1:89, 2:3, 3:0, 4:5}</code>?
I checked some posts but they all use the ""sorted"" operator that returns tuples. 
"
9039961|"Finding the average of a list"|"I have to find the average of a list in Python. This is my code so far

<code>l = [15, 18, 2, 36, 12, 78, 5, 6, 9]
print reduce(lambda x, y: x + y, l)
</code>

I've got it so it adds together the values in the list, but I don't know how to make it divide into them?
"
9252543|"ImportError: Cannot import name X"|"I have four different files named: main, vector, entity, and physics. I will not post all the code, mostly just the imports, because I think that's where the error is. But if you want, I can post more.

Main:

<code>import time
from entity import Ent
from vector import Vect
#the rest just creates an entity and prints the result of movement
</code>

Entity:

<code>from vector import Vect
from physics import Physics
class Ent:
    #holds vector information and id
def tick(self, dt):
    #this is where physics changes the velocity and position vectors
</code>

Vector:

<code>from math import *
class Vect:
    #holds i, j, k, and does vector math
</code>

Physics:

<code>from entity import Ent
class Physics:
    #physics class gets an entity and does physics calculations on it.
</code>

I then run from main.py and I get the following error:

<code>Traceback (most recent call last):
File ""main.py"", line 2, in &lt;module&gt;
    from entity import Ent
File "".../entity.py"", line 5, in &lt;module&gt;
    from physics import Physics
File "".../physics.py"", line 2, in &lt;module&gt;
    from entity import Ent
ImportError: cannot import name Ent
</code>

I am very new to python, but have worked with C++ for a long time. I am guessing that the cause is from importing entity twice, once in main, and later in physics, but I don't know a workaround. Anyone help?
"
9257094|"How to change a string into uppercase"|"I have problem in changing a string into uppercase with Python. In my research, I got <code>string.ascii_uppercase</code> but it doesn't work.

The following code:

<code> &gt;&gt;s = 'sdsd'
 &gt;&gt;s.ascii_uppercase
</code>

Gives this error message:

<code>Traceback (most recent call last):
  File ""&lt;console&gt;"", line 1, in &lt;module&gt;
AttributeError: 'str' object has no attribute 'ascii_uppercase'
</code>

My question is: how can I convert a string into uppercase in Python?
"
9316023|"Python 2.7: Print to File"|"Why does trying to print directly to a file instead of <code>sys.stdout</code> produce the following syntax error:

<code>Python 2.7.2+ (default, Oct  4 2011, 20:06:09)
[GCC 4.6.1] on linux2
Type ""help"", ""copyright"", ""credits"" or ""license"" for more information.
&gt;&gt;&gt; f1=open('./testfile', 'w+')
&gt;&gt;&gt; print('This is a test', file=f1)
  File ""&lt;stdin&gt;"", line 1
    print('This is a test', file=f1)
                            ^
SyntaxError: invalid syntax
</code>

From help(__builtins__) I have the following info:

<code>print(...)
    print(value, ..., sep=' ', end='\n', file=sys.stdout)

    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file: a file-like object (stream); defaults to the current sys.stdout.
    sep:  string inserted between values, default a space.
    end:  string appended after the last value, default a newline.
</code>

So what would be the right syntax to change the standard stream print writes to?

I know that there are different maybe better ways to write to file but I really don't get why this should be a syntax error...

A nice explanation would be appreciated!
"
9542738|"Python: Find in list"|"I have come across this delightful:

<code>item = someSortOfSelection()
if item in myList:
    doMySpecialFunction(item)
</code>

but sometimes it does not work with all my items, as if they weren't recognized in the list (when it's a list of string).

is it the most 'pythonic' way of finding an item in a list: <code>if x in l:</code>?
"
9573244|"Most elegant way to check if the string is empty in Python?"|"Does Python have something like an empty string variable where you can do?:

<code>if myString == string.empty:
</code>

Regardless what's the most elegant way to check for empty string values? I find hard coding <code>""""</code> every time for checking an empty string not as good.
"
9622163|"Save plot to image file instead of displaying it using Matplotlib"|"I am writing a quick-and-dirty script to generate plots on the fly. I am using the code below (from Matplotlib documentation) as a starting point:

<code>from pylab import figure, axes, pie, title, show

# Make a square figure and axes
figure(1, figsize=(6, 6))
ax = axes([0.1, 0.1, 0.8, 0.8])

labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
fracs = [15, 30, 45, 10]

explode = (0, 0.05, 0, 0)
pie(fracs, explode=explode, labels=labels, autopct='%1.1f%%', shadow=True)
title('Raining Hogs and Dogs', bbox={'facecolor': '0.8', 'pad': 5})

show()  # Actually, don't show, just save to foo.png
</code>

I don't want to display the plot on a GUI, instead, I want to save the plot to a file (say foo.png), so that, for example, it can be used in batch scripts. How do I do that?
"
9641440|"Convert from ASCII string encoded in Hex to plain ASCII?"|"How can I convert from hex to plain ASCII in Python?

Note that, for example, I want to convert ""0x7061756c"" to ""paul"".
"
9733638|"Post JSON using Python Requests"|"I need to POST a JSON from a client to a server. I'm using Python 2.7.1 and simplejson. The client is using Requests. The server is CherryPy. I can GET a hard-coded JSON from the server (code not shown), but when I try to POST a JSON to the server, I get ""400 Bad Request"".

Here is my client code:

<code>data = {'sender':   'Alice',
    'receiver': 'Bob',
    'message':  'We did it!'}
data_json = simplejson.dumps(data)
payload = {'json_payload': data_json}
r = requests.post(""http://localhost:8080"", data=payload)
</code>

Here is the server code.

<code>class Root(object):

    def __init__(self, content):
        self.content = content
        print self.content  # this works

    exposed = True

    def GET(self):
        cherrypy.response.headers['Content-Type'] = 'application/json'
        return simplejson.dumps(self.content)

    def POST(self):
        self.content = simplejson.loads(cherrypy.request.body.read())
</code>

Any ideas?
"
9752958|"How can I return two values from a function in Python?"|"I would like to return two values from a function in two separate variables. 
For example:

<code>def select_choice():
    loop = 1
    row = 0
    while loop == 1:
        print('''Choose from the following options?:
                 1. Row 1
                 2. Row 2
                 3. Row 3''')

        row = int(input(""Which row would you like to move the card from?: ""))
        if row == 1:
            i = 2
            card = list_a[-1]
        elif row == 2:
            i = 1
            card = list_b[-1]
        elif row == 3:
            i = 0
            card = list_c[-1]
        return i
        return card
</code>

And I want to be able to use these values separately. When I tried to use <code>return i, card</code>, it returns a <code>tuple</code> and this is not what I want. 
"
9780717|"bash: pip: command not found"|"I downloaded pip and ran <code>python setup.py install</code> and everything worked just fine. The very next step in the tutorial is to run <code>pip install &lt;lib you want&gt;</code> but before it even tries to find anything online I get an error ""bash: pip: command not found"".

This is on Mac OS X, which I'm new too, so I'm assuming there's some kind of path setting that was not set correctly when I ran setup.py. How can I investigate further? What do I need to check to get a better idea of the exact cause of the problem?

EDIT: I also tried installing Python 2.7 for Mac in the hopes that the friendly install process would do any housekeeping like editing PATH and whatever else needs to happy for everything to work according to the tutorials, but this didn't work. After installing is running 'python' still ran Python 2.6 and PATH was not updated.
"
9835762|"Find and list duplicates in a list?"|"How can I find the duplicates in a Python list and create another list of the duplicates?  The list is just integers.
"
9847213|"which day of week given a date python"|"I want to find out the following:
given a date (<code>datetime</code> object), what is the corresponding day of the week.

For instance Sunday is the first day, Monday: second day.. and so on

And then if the input is something like Today's date.
The output is maybe <code>6</code> (since its Friday)
"
9942594|"UnicodeEncodeError: 'ascii' codec can't encode character u'\xa0' in position 20: ordinal not in range(128)"|"I'm having problems dealing with unicode characters from text fetched from different web pages (on different sites). I am using BeautifulSoup. 

The problem is that the error is not always reproducible; it sometimes works with some pages, and sometimes, it barfs by throwing a <code>UnicodeEncodeError</code>. I have tried just about everything I can think of, and yet I have not found anything that works consistently without throwing some kind of Unicode-related error.

One of the sections of code that is causing problems is shown below:

<code>agent_telno = agent.find('div', 'agent_contact_number')
agent_telno = '' if agent_telno is None else agent_telno.contents[0]
p.agent_info = str(agent_contact + ' ' + agent_telno).strip()
</code>

Here is a stack trace produced on SOME strings when the snippet above is run:

<code>Traceback (most recent call last):
  File ""foobar.py"", line 792, in &lt;module&gt;
    p.agent_info = str(agent_contact + ' ' + agent_telno).strip()
UnicodeEncodeError: 'ascii' codec can't encode character u'\xa0' in position 20: ordinal not in range(128)
</code>

I suspect that this is because some pages (or more specifically, pages from some of the sites) may be encoded, whilst others may be unencoded. All the sites are based in the UK and provide data meant for UK consumption - so there are no issues relating to internalization or dealing with text written in anything other than English.

Does anyone have any ideas as to how to solve this so that I can CONSISTENTLY fix this problem?
"
10017147|"Removing a list of characters in string"|"I want to remove characters in a string in python:

<code>string.replace(',', '').replace(""!"", '').replace("":"", '').replace("";"", '')...
</code>

But I have many characters I have to remove. I thought about a list

<code>list = [',', '!', '.', ';'...]
</code>

But how can I use the <code>list</code> to replace the characters in the <code>string</code>?
"
10116518|"I'm getting Key error in python"|"In my python program I am getting this error:

<code>KeyError: 'variablename'
</code>

From this code:

<code>path = meta_entry['path'].strip('/'),
</code>

Can anyone please explain why this is happening?
"
10147455|"How to send an email with Gmail as provider using Python?"|"I am trying to send email (Gmail) using python, but I am getting following error.

<code>Traceback (most recent call last):  
File ""emailSend.py"", line 14, in &lt;module&gt;  
server.login(username,password)  
File ""/usr/lib/python2.5/smtplib.py"", line 554, in login  
raise SMTPException(""SMTP AUTH extension not supported by server."")  
smtplib.SMTPException: SMTP AUTH extension not supported by server.
</code>

The Python script is the following.

<code>import smtplib
fromaddr = 'user_me@gmail.com'
toaddrs  = 'user_you@gmail.com'
msg = 'Why,Oh why!'
username = 'user_me@gmail.com'
password = 'pwd'
server = smtplib.SMTP('smtp.gmail.com:587')
server.starttls()
server.login(username,password)
server.sendmail(fromaddr, toaddrs, msg)
server.quit()
</code>
"
10434599|"How to get data received in Flask request"|"I want to be able to get the data sent to my Flask app.  I've tried accessing <code>request.data</code> but it is an empty string. How do you access request data?

<code>@app.route('/', methods=['GET', 'POST'])
def parse_request():
    data = request.data  # data is empty
    # need posted data here
</code>



The answer to this question led me to ask Get raw POST body in Python Flask regardless of Content-Type header next, which is about getting the raw data rather than the parsed data.
"
10458437|"What is the difference between dict.items() and dict.iteritems()?"|"Are there any applicable differences between <code>dict.items()</code> and <code>dict.iteritems()</code>?

From the Python docs:


  <code>dict.items()</code>: Return a copy of the dictionary’s list of (key, value) pairs.
  
  <code>dict.iteritems()</code>: Return an iterator over the dictionary’s (key, value) pairs.


If I run the code below, each seems to return a reference to the same object. Are there any subtle differences that I am missing?

<code>#!/usr/bin/python

d={1:'one',2:'two',3:'three'}
print 'd.items():'
for k,v in d.items():
   if d[k] is v: print '\tthey are the same object' 
   else: print '\tthey are different'

print 'd.iteritems():'   
for k,v in d.iteritems():
   if d[k] is v: print '\tthey are the same object' 
   else: print '\tthey are different'   
</code>

Output:

<code>d.items():
    they are the same object
    they are the same object
    they are the same object
d.iteritems():
    they are the same object
    they are the same object
    they are the same object
</code>
"
10561923|"UnicodeDecodeError: 'ascii' codec can't decode byte 0xef in position 1"|"I'm having a few issues trying to encode a string to UTF-8. I've tried numerous things, including using <code>string.encode('utf-8')</code> and <code>unicode(string)</code>, but I get the error:


  UnicodeDecodeError: 'ascii' codec can't decode byte 0xef in position 1: ordinal not in range(128)


This is my string:

<code>(｡･ω･｡)ﾉ
</code>

I don't see what's going wrong, any idea?

Edit: The problem is that printing the string as it is does not show properly. Also, this error when I try to convert it:

<code>Python 2.7.1+ (r271:86832, Apr 11 2011, 18:13:53)
[GCC 4.5.2] on linux2
Type ""help"", ""copyright"", ""credits"" or ""license"" for more information.
&gt;&gt;&gt; s = '(\xef\xbd\xa1\xef\xbd\xa5\xcf\x89\xef\xbd\xa5\xef\xbd\xa1)\xef\xbe\x89'
&gt;&gt;&gt; s1 = s.decode('utf-8')
&gt;&gt;&gt; print s1
Traceback (most recent call last):
  File ""&lt;stdin&gt;"", line 1, in &lt;module&gt;
UnicodeEncodeError: 'ascii' codec can't encode characters in position 1-5: ordinal not in range(128)
</code>
"
10588317|"Python function global variables?"|"So I know I should avoid using global variables in the first place due to confusion like this, but if I were to use them, is the following a valid way to go about using them? (I am trying to call the global copy of a variable created in a separate function.)

<code>x = somevalue

def func_A ():
   global x
   # do things to x
   return x

def func_B():
   x=func_A()
   # do things
   return x

func_A()
func_B()
</code>

Does the <code>x</code> that the second function uses have the same value of the global copy of <code>x</code> that <code>func_a</code> uses and modifies? When calling the functions after definition, does order matter?
"
10660435|"Pythonic way to create a long multi-line string"|"I have a very long query. I would like to split it in several lines in Python. A way to do it in JavaScript would be using several sentences and joining them with a <code>+</code> operator (I know, maybe it's not the most efficient way to do it, but I'm not really concerned about performance in this stage, just code readability). Example:

<code>var long_string = 'some text not important. just garbage to' +
                  'illustrate my example';
</code>

I tried doing something similar in Python, but it didn't work, so I used <code>\</code> to split the long string. However, I'm not sure if this is the only/best/pythonicest way of doing it. It looks awkward. 
Actual code:

<code>query = 'SELECT action.descr as ""action"", '\
    'role.id as role_id,'\
    'role.descr as role'\
    'FROM '\
    'public.role_action_def,'\
    'public.role,'\
    'public.record_def, '\
    'public.action'\
    'WHERE role.id = role_action_def.role_id AND'\
    'record_def.id = role_action_def.def_id AND'\
    'action.id = role_action_def.action_id AND'\
    'role_action_def.account_id = ' + account_id + ' AND'\
    'record_def.account_id=' + account_id + ' AND'\
    'def_id=' + def_id
</code>
"
10667960|"Python Requests throwing up SSLError"|"I'm working on a simple script that involves CAS, jspring security check, redirection, etc.  I would like to use Kenneth Reitz's python requests because it's a great piece of work!  However, CAS requires getting validated via SSL so I have to get past that step first.  I don't know what Python requests is wanting?  Where is this SSL certificate suppose to reside?

<code>Traceback (most recent call last):
  File ""./test.py"", line 24, in &lt;module&gt;
  response = requests.get(url1, headers=headers)
  File ""build/bdist.linux-x86_64/egg/requests/api.py"", line 52, in get
  File ""build/bdist.linux-x86_64/egg/requests/api.py"", line 40, in request
  File ""build/bdist.linux-x86_64/egg/requests/sessions.py"", line 209, in request 
  File ""build/bdist.linux-x86_64/egg/requests/models.py"", line 624, in send
  File ""build/bdist.linux-x86_64/egg/requests/models.py"", line 300, in _build_response
  File ""build/bdist.linux-x86_64/egg/requests/models.py"", line 611, in send
requests.exceptions.SSLError: [Errno 1] _ssl.c:503: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
</code>
"
10712002|"Create an empty list in python with certain size"|"I want to create an empty list (or whatever is the best way) that can hold 10 elements.

After that I want to assign values in that list, for example this is supposed to display 0 to 9:

<code>s1 = list();
for i in range(0,9):
   s1[i] = i

print  s1
</code>

But when I run this code, it generates an error or in another case it just displays <code>[]</code> (empty). 

Can someone explain why?
"
10715965|"add one row in a pandas.DataFrame"|"I understand that pandas is designed to load fully populated <code>DataFrame</code> but I need to create an empty DataFrame then add rows, one by one.
What is the best way to do this ?

I successfully created an empty DataFrame with :

<code>res = DataFrame(columns=('lib', 'qty1', 'qty2'))
</code>

Then I can add a new row and fill a field with :

<code>res = res.set_value(len(res), 'qty1', 10.0)
</code>

It works but seems very odd :-/ (it fails for adding string value)

How can I add a new row to my DataFrame (with different columns type) ?
"
10763440|"How to install python3 version of package via pip on Ubuntu?"|"I have both <code>python2.7</code> and <code>python3.2</code> installed in <code>Ubuntu 12.04</code>.
The symbolic link <code>python</code> links to <code>python2.7</code>.

When I type:

<code>sudo pip install package-name
</code>

It will default install <code>python2</code> version of <code>package-name</code>.

Some package supports both <code>python2</code> and <code>python3</code>.
How to install <code>python3</code> version of <code>package-name</code> via <code>pip</code>?
"
10973766|"Understanding the map function"|"<code>map(function, iterable, ...)
</code>

Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel. 

If one iterable is shorter than another it is assumed to be extended with None items. 

If function is <code>None</code>, the identity function is assumed; if there are multiple arguments, <code>map()</code> returns a list consisting of tuples containing the corresponding items from all iterables (a kind of transpose operation). 

The iterable arguments may be a sequence or any iterable object; the result is always a list.

What role does this play in making a Cartesian product?

<code>content = map(tuple, array)
</code>

What effect does putting a tuple anywhere in there have? I also noticed that without the map function the output is <code>abc</code> and with it, it's <code>a, b, c</code>.

I want to fully understand this function. The reference definitions is also hard to understand. Too much fancy fluff. 
"
11060506|"Is there a ""not equal"" operator in Python?"|"How would you say does not equal?

Like 

<code>if hi == hi:
    print ""hi""
elif hi (does not equal) bye:
    print ""no hi""
</code>

Is there a replacement for <code>==</code> that means ""not equal""?
"
11094718|"error: command 'gcc' failed with exit status 1 while installing eventlet"|"I wanted to install <code>eventlet</code> on my system in order to have ""Herd"" for software deployment.. but the terminal is showing a gcc error:

<code>  root@agrover-OptiPlex-780:~# easy_install -U eventlet
  Searching for eventlet
  Reading http://pypi.python.org/simple/eventlet/
  Reading http://wiki.secondlife.com/wiki/Eventlet
  Reading http://eventlet.net
   Best match: eventlet 0.9.16
    Processing eventlet-0.9.16-py2.7.egg
    eventlet 0.9.16 is already the active version in easy-install.pth

   Using /usr/local/lib/python2.7/dist-packages/eventlet-0.9.16-py2.7.egg
 Processing dependencies for eventlet
 Searching for greenlet&gt;=0.3
Reading http://pypi.python.org/simple/greenlet/
Reading https://github.com/python-greenlet/greenlet
Reading http://bitbucket.org/ambroff/greenlet
Best match: greenlet 0.3.4
Downloading http://pypi.python.org/packages/source/g/greenlet/greenlet-   0.3.4.zip#md5=530a69acebbb0d66eb5abd83523d8272
Processing greenlet-0.3.4.zip
Writing /tmp/easy_install-_aeHYm/greenlet-0.3.4/setup.cfg
Running greenlet-0.3.4/setup.py -q bdist_egg --dist-dir /tmp/easy_install-_aeHYm/greenlet-0.3.4/egg-dist-tmp-t9_gbW
In file included from greenlet.c:5:0:
greenlet.h:8:20: fatal error: Python.h: No such file or directory
compilation terminated.
error: Setup script exited with error: command 'gcc' failed with exit status 1`
</code>

Why can't <code>Python.h</code> be found?
"
11178061|"Print list without brackets in a single row"|"I have a list in Python
e.g.

<code>names = [""Sam"", ""Peter"", ""James"", ""Julian"", ""Ann""]
</code>

I want to print the array in a single line without the normal "" []

<code>names = [""Sam"", ""Peter"", ""James"", ""Julian"", ""Ann""]
print (names)
</code>

Will give the output as;

<code>[""Sam"", ""Peter"", ""James"", ""Julian"", ""Ann""]
</code>

That is not the format I want instead I want it to be like this;

<code>Sam, Peter, James, Julian, Ann
</code>

Note: It must be in a single row.
"
11200137|"Installing Numpy on 64bit Windows 7 with Python 2.7.3"|"It looks like the only 64 bit windows installer for Numpy is for Numpy version 1.3.0 which only works with Python 2.6

http://sourceforge.net/projects/numpy/files/NumPy/

It strikes me as strange that I would have to roll back to Python 2.6 to use Numpy on Windows, which makes me think I'm missing something.

Am I?
"
11266068|"Python: avoid new line with print command"|"I've started programming today and have this issue with Python. It's pretty dumb but I can't figure out how to do it. When I use the print command, it prints whatever I want and then goes to a different line. For example: 

<code>print ""this should be""; print ""on the same line""
</code>

Should return: 


  this should be on the same line


but instead returns: 


  this should be
  on the same line


More precisely I was trying to create a program with <code>if</code> that told me whether a number was a 2 or not

<code>def test2(x):
    if x == 2:
        print ""Yeah bro, that's tottaly a two""
    else:
        print ""Nope, that is not a two. That is a (x)""
</code>

But it doesn't recognise the last <code>(x)</code> as the value entered, and rather prints exactly: ""(x)"" (the letter with the brackets). To make it work I have to write:

<code>print ""Nope, that is not a two. That is a""; print (x)
</code>

And if e.g. I enter <code>test2(3)</code> that gives:


  Nope, that is not a two, that is a
  3


So either i need to make Python recognise my (x) inside a print line as the number; or to print two separate things but on the same line. 
Thanks in advance and sorry for such a stupid question.

IMPORTANT NOTE: I am using version 2.5.4

Another note: If i put <code>print ""Thing"" , print ""Thing2""</code> it says ""Syntax error"" on the 2nd print.
"
11277432|"How to remove a key from a python dictionary?"|"When trying to delete a key from a dictionary, I write:

<code>if 'key' in myDict:
    del myDict['key']
</code>

Is there a one line way of doing this?
"
11285613|"Selecting columns"|"I have data in different columns but I don't know how to extract it to save it in another variable.

<code>index  a   b   c
1      2   3   4
2      3   4   5
</code>

How do I select <code>'b'</code>, <code>'c'</code> and save it in to df1?

I tried 

<code>df1 = df['a':'b']
df1 = df.ix[:, 'a':'b']
</code>

None seem to work. Any ideas would help thanks.
"
11346283|"Renaming columns in pandas"|"I have a data table using pandas and column labels that I need to edit to replace the original column labels. 

I'd like to change the column names in a data table <code>A</code> where the original column names are:

<code>['$a', '$b', '$c', '$d', '$e'] 
</code>

to 

<code>['a', 'b', 'c', 'd', 'e'].
</code>

I have the edited column names stored it in a list, but I don't know how to replace the column names.
"
11425106|"Python pip install fails: invalid command egg_info"|"I find that recently often when I try to install a Python package using pip, I get the error(s) below.

I found a reference online that one has to use ""python2 setup.py install"" from the download directory, and indeed find that this will then work if I manually find and download the package (from pypi).

But, I don't know where pip is downloading packages to, and/or why it is failing in this manner.

I tried to do a pip upgrade, but it also failed in a similar manner, with a bunch of ""Unknown distribution option"" errors (entry_points, zip_safe, test_suite, tests_require)!


pip 1.0.1
ActivePython 2.7


Trying to use ActiveState's pypm fails, because they have a smaller library base, and it doesn't include these packages.

<code>C:\test&gt;pip install requests-oauth
Downloading/unpacking requests-oauth
  Downloading requests-oauth-0.4.1.tar.gz
  Running setup.py egg_info for package requests-oauth
    E:\Plang\ActivePython\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'zip_safe'
      warnings.warn(msg)
    E:\Plang\ActivePython\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'install_requires'
      warnings.warn(msg)
    usage: -c [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
       or: -c --help [cmd1 cmd2 ...]
       or: -c --help-commands
       or: -c cmd --help

    error: invalid command 'egg_info'
    Complete output from command python setup.py egg_info:
    E:\Plang\ActivePython\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'zip_safe'
  warnings.warn(msg)

E:\Plang\ActivePython\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'install_requires'
  warnings.warn(msg)

usage: -c [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
   or: -c --help [cmd1 cmd2 ...]
   or: -c --help-commands
   or: -c cmd --help

error: invalid command 'egg_info'
</code>
"
11497376|"How would I specify a new line in Python?"|"How would I specify a new line in python?

For a comparison to Java in a String you would do something like ""First Line\r\nSecond Line""

So How would you do that in Python? For purposes of saving files with more then one line.
"
11520492|"Difference between del, remove and pop on lists"|"<code>&gt;&gt;&gt; a=[1,2,3]
&gt;&gt;&gt; a.remove(2)
&gt;&gt;&gt; a
[1, 3]
&gt;&gt;&gt; a=[1,2,3]
&gt;&gt;&gt; del a[1]
&gt;&gt;&gt; a
[1, 3]
&gt;&gt;&gt; a= [1,2,3]
&gt;&gt;&gt; a.pop(1)
2
&gt;&gt;&gt; a
[1, 3]
&gt;&gt;&gt; 
</code>

Is there any difference between the above three methods to remove an element from a list?
"
11536764|"How to fix ""Attempted relative import in non-package"" even with __init__.py"|"I'm trying to follow PEP 328, with the following directory structure:

<code>pkg/
  __init__.py
  components/
    core.py
    __init__.py
  tests/
    core_test.py
    __init__.py
</code>

In <code>core_test.py</code> I have the following import statement

<code>from ..components.core import GameLoopEvents
</code>

However, when I run, I get the following error:

<code>tests$ python core_test.py 
Traceback (most recent call last):
  File ""core_test.py"", line 3, in &lt;module&gt;
    from ..components.core import GameLoopEvents
ValueError: Attempted relative import in non-package
</code>

Searching around I found ""relative path not working even with __init__.py"" and ""Import a module from a relative path"" but they didn't help.

Is there anything I'm missing here?
"
11552320|"Correct way to pause Python program"|"I've been using the input function as a way to pause my scripts

<code>print(""something"")
wait = input(""PRESS ENTER TO CONTINUE."")
print(""something"")
</code>

is there a formal way to do this?
"
11555468|"How should I read a file line-by-line in Python?"|"In pre-historic times (Python 1.4) we did:

<code>fp = open('filename.txt')
while 1:
    line = fp.readline()
    if not line:
        break
    print line
</code>

after Python 2.1, we did:

<code>for line in open('filename.txt').xreadlines():
    print line
</code>

before we got the convenient iterator protocol in Python 2.3, and could do:

<code>for line in open('filename.txt'):
    print line
</code>

I've seen some examples using the more verbose:

<code>with open('filename.txt') as fp:
    for line in fp:
        print line
</code>

is this the preferred method going forwards?

[edit] I get that the with statement ensures closing of the file... but why isn't that included in the iterator protocol for file objects?
"
11618898|"pg_config executable not found"|"I am having trouble installing psycopg2. I get the following error when I try to <code>pip install psycopg2</code>:

<code>Error: pg_config executable not found.

Please add the directory containing pg_config to the PATH

or specify the full executable path with the option:



    python setup.py build_ext --pg-config /path/to/pg_config build ...



or with the pg_config option in 'setup.cfg'.

----------------------------------------
Command python setup.py egg_info failed with error code 1 in /tmp/pip-build/psycopg2
</code>

But the problem is <code>pg_config</code> is actually in my <code>PATH</code>; it runs without any problem:

<code>$ which pg_config
/usr/pgsql-9.1/bin/pg_config
</code>

I tried adding the pg_config path to the <code>setup.cfg</code> file and building it using the source files I downloaded from their website (http://initd.org/psycopg/) and I get the following error message!

<code>Error: Unable to find 'pg_config' file in '/usr/pgsql-9.1/bin/'
</code>

But it is actually THERE!!!

I am baffled by these errors. Can anyone help please?

By the way, I <code>sudo</code> all the commands. Also I am on RHEL 5.5.
"
11880430|"How to write inline if statement for print?"|"I need to print some stuff only when a boolean variable is set to <code>True</code>. So, after looking at this, I tried with a simple example:

<code>&gt;&gt;&gt; a = 100
&gt;&gt;&gt; b = True
&gt;&gt;&gt; print a if b
  File ""&lt;stdin&gt;"", line 1
    print a if b
             ^
SyntaxError: invalid syntax  
</code>

Same thing if I write <code>print a if b==True</code>.

What am I missing here?
"
12169839|"Which is the preferred way to concatenate a string in Python?"|"Since Python's <code>string</code> can't be changed, I was wondering how to concatenate a string more efficiently?

I can write like it:

<code>s += stringfromelsewhere
</code>

or like this:

<code>s = []
s.append(somestring)

later

s = ''.join(s)
</code>

While writing this question, I found a good article talking about the topic.

http://www.skymind.com/~ocrow/python_string/

But it's in Python 2.x., so the question would be did something change in Python 3?
"
12179271|"Meaning of @classmethod and @staticmethod for beginner?"|"Could someone explain to me the meaning of <code>@classmethod</code> and <code>@staticmethod</code> in python? I need to know the difference and the meaning. 

As far as I understand, <code>@classmethod</code> tells a class that it's a method which should be inherited into subclasses, or... something. However, what's the point of that? Why not just define the class method without adding <code>@classmethod</code> or <code>@staticmethod</code> or any <code>@</code> definitions?

tl;dr: when should I use them, why should I use them, and how should I use them?

I'm pretty advanced with C++, so using more advanced programming concepts shouldn't be a problem. Feel free giving me a corresponding C++ example if possible.
"
12214801|"Print a string as hex bytes?"|"I have this string: <code>Hello world !!</code> and I want to print it using Python as <code>48:65:6c:6c:6f:20:77:6f:72:6c:64:20:21:21</code>.

<code>hex()</code> works only for integers. 

How can it be done?
"
12309269|"How do I write JSON data to a file?"|"I have JSON data stored in the variable <code>data</code>.

I want to write this to a text file for testing so I don't have to grab the data from the server each time.

Currently, I am trying this:

<code>obj = open('data.txt', 'wb')
obj.write(data)
obj.close
</code>

And am receiving the error: 

<code>TypeError: must be string or buffer, not dict</code>

How to fix this?
"
12323403|"How do I find an element that contains specific text in Selenium Webdriver (Python)?"|"I'm trying to test a complicated javascript interface with Selenium (using the Python interface, and across multiple browsers).  I have a number of buttons of the form:

<code>&lt;div&gt;My Button&lt;/div&gt;
</code>

I'd like to be able to search for buttons based on ""My Button"" (or non-case-sensitive, partial matches such as ""my button"" or ""button"")

I'm finding this amazingly difficult, to the extent to which I feel like I'm missing something obvious.  The best thing I have so far is:

<code>driver.find_elements_by_xpath('//div[contains(text(), ""' + text + '"")]')
</code>

This is case-sensitive, however.  The other thing I've tried is iterating through all the divs on the page, and checking the element.text property.  However, every time you get a situation of the form:

<code>&lt;div class=""outer""&gt;&lt;div class=""inner""&gt;My Button&lt;/div&gt;&lt;/div&gt;
</code>

div.outer also has ""My Button"" as the text.  To fix THAT, I've tried looking to see if div.outer is the parent of div.inner, but couldn't figure out how to do that (element.get_element_by_xpath('..') returns an element's parent, but it tests not equal to div.outer).  Also, iterating through all the elements on the page seems to be really slow, at least using the Chrome webdriver.

Ideas?

Edit: This question came out a little vague.  Asked (and answered) a more specific version here: How to get text of an element in Selenium WebDriver (via the Python api) without including child element text?
"
12453580|"Concatenate item in list to strings"|"Is there a simpler way to concatenate string items in list into a single string?

Can I use the <code>str.join()</code> function to join items in list?

E.g. this is the input <code>['this','is','a','sentence']</code> and this is the desired output <code>this-is-a-sentence</code>

<code>sentence = ['this','is','a','sentence']
sent_str = """"
for i in sentence:
    sent_str += str(i) + ""-""
sent_str = sent_str[:-1]
print sent_str
</code>
"
12468179|"UnicodeDecodeError: 'utf8' codec can't decode byte 0x9c"|"I have a socket server that is supposed to receive UTF-8 valid characters from clients.

The problem is some clients (mainly hackers) are sending all the wrong kind of data over it.

I can easily distinguish the genuine client, but I am logging to files all the data sent so I can analyze it later.

Sometimes I get characters like this <code>œ</code> that cause the <code>UnicodeDecodeError</code> error.

I need to be able to make the string UTF-8 with or without those characters.
"
12555323|"Adding new column to existing DataFrame in Python pandas"|"I have the following indexed DataFrame with named columns and rows not- continuous numbers:

<code>          a         b         c         d
2  0.671399  0.101208 -0.181532  0.241273
3  0.446172 -0.243316  0.051767  1.577318
5  0.614758  0.075793 -0.451460 -0.012493
</code>

I would like to add a new column, <code>'e'</code>, to the existing data frame and do not want to change anything in the data frame (i.e., the new column always has the same length as the DataFrame). 

<code>0   -0.335485
1   -1.166658
2   -0.385571
dtype: float64
</code>

I tried different versions of <code>join</code>, <code>append</code>, <code>merge</code>, but I did not get the result I wanted, only errors at most. How can I add column <code>e</code> to the above example? 
"
12608788|"Changing the ""tick frequency"" on x or y axis in matplotlib?"|"I am trying to fix how python plots my data.

Say 

<code>x = [0,5,9,10,15]
</code>

and 

<code>y = [0,1,2,3,4]
</code>

Then I would do:

<code>matplotlib.pyplot.plot(x,y)
matplotlib.pyplot.show()
</code>

and the x axis' ticks are plotted in intervals of 5. Is there a way to make it show intervals of 1?
"
12754680|"Modulo operator in Python"|"What does modulo in the following piece of code do?

<code>from math import *
3.14 % 2 * pi
</code>

How do we calculate modulo on a floating point number?
"
12836128|"Convert list to tuple in Python"|"I'm trying to convert a list to a tuple. 

When I google it, I find a lot of answers similar to:

<code>l = [4,5,6]
tuple(l)
</code>

But if I do that I get this error message:


  TypeError: 'tuple' object is not callable


How can I fix this problem?
"
12897374|"Get unique values from a list in python"|"I want to get the unique values from the following list:

<code>[u'nowplaying', u'PBS', u'PBS', u'nowplaying', u'job', u'debate', u'thenandnow']
</code>

The output which I require is:

<code>[u'nowplaying', u'PBS', u'job', u'debate', u'thenandnow']
</code>

I tried the following code:

<code>output = []
for x in trends:
    if x not in output:
        output.append(x)
print output
</code>

but it didn't work. Any help would be appreciated.
"
12934190|"Is there a short contains function for lists?"|"I see people are using <code>any</code> to gather another list to see if an item exists in a list, but is there a quick way to just do?:

<code>if list.contains(myItem):
    # do something
</code>
"
12943819|"How to prettyprint a JSON file?"|"I have a JSON file that is a mess that I want to prettyprint-- what's the easiest way to do this in python? I know PrettyPrint takes an ""object"", which I think can be a file, but I don't know how to pass a file in-- just using the filename doesn't work.
"
13411544|"Delete column from pandas DataFrame"|"When deleting a column in a DataFrame I use:

<code>del df['column_name']
</code>

and this works great. Why can't I use:

<code>del df.column_name
</code>

As you can access the column/Series as <code>df.column_name</code>, I expect this to work.
"
13413590|"How to drop rows of Pandas DataFrame whose value in certain columns is NaN"|"I have a <code>DataFrame</code>:

<code>&gt;&gt;&gt; df
                 STK_ID  EPS  cash
STK_ID RPT_Date                   
601166 20111231  601166  NaN   NaN
600036 20111231  600036  NaN    12
600016 20111231  600016  4.3   NaN
601009 20111231  601009  NaN   NaN
601939 20111231  601939  2.5   NaN
000001 20111231  000001  NaN   NaN
</code>

Then I just want the records whose <code>EPS</code> is not <code>NaN</code>, that is, <code>df.drop(....)</code> will return the dataframe as below:

<code>                  STK_ID  EPS  cash
STK_ID RPT_Date                   
600016 20111231  600016  4.3   NaN
601939 20111231  601939  2.5   NaN
</code>

How do I do that?
"
13437727|"Python - Write to Excel Spreadsheet"|"I am new to Python. I need to write some data from my program to a spreadsheet. I've searched online and there seems to be many packages available (xlwt, XlsXcessive, openpyxl). Others suggest to write to a csv file (never used csv &amp; don't really understand what it is).

The program is very simple. I have two lists (float) and three variables (strings). I don't know the lengths of the two lists and they probably won't be the same length.

I want the layout to be as in the picture below:



The pink column will have the values of the first list and the green column will have the values of the second list.

So what's the best way to do this? Thanks.

P.S. I am running Windows 7 but I won't necessarily have Office installed on the computers running this program.

EDIT

<code>import xlwt

x=1
y=2
z=3

list1=[2.34,4.346,4.234]

book = xlwt.Workbook(encoding=""utf-8"")

sheet1 = book.add_sheet(""Sheet 1"")

sheet1.write(0, 0, ""Display"")
sheet1.write(1, 0, ""Dominance"")
sheet1.write(2, 0, ""Test"")

sheet1.write(0, 1, x)
sheet1.write(1, 1, y)
sheet1.write(2, 1, z)

sheet1.write(4, 0, ""Stimulus Time"")
sheet1.write(4, 1, ""Reaction Time"")

i=4

for n in list1:
    i = i+1
    sheet1.write(i, 0, n)



book.save(""trial.xls"")
</code>

I wrote this using all your suggestions. It gets the job done but it can be slightly improved. How do I format the cells created in the for loop (list1 values) as scientific or number? I do not want to truncate the values. The actual values used in the program would have around 10 digits after the decimal.
"
13628791|"How do I check whether an int is between the two numbers?"|"I'm using 2.3 IDLE and I'm having problems.

I need to check whether a number is between two other numbers, 10000 and 30000:

<code>if number &gt;= 10000 and number &gt;= 30000:
    print (""you have to pay 5% taxes"")
</code>

It's not working too well.
"
13636640|"python - checking odd/even numbers and changing outputs on number size"|"I have a couple of problems to solve for an assignment, and am a bit stuck.
The question is to write a program that gets the user to input an odd number (check it's odd), then print an upside down pyramid of stars based on the size of the input.

For example, if you enter 5, it comes up with

<code>*****
 ***
  *
</code>

My problem is therefore two-fold.

1) How do I check if it's even or odd? I tried <code>if number/2 == int</code> in the hope that it might do something, and the internet tells me to do <code>if number%2==0</code>, but that doesn't work.

2) How do I change the asterisks in the middle of each line?

Any help with either problem is greatly appreciated.
"
13704860|"zip lists in python"|"I am a python newbie and I am trying to learn how to ""zip"" lists. To this end, I have a program, where at a particular point, I do the following:

<code>x1, x2, x3 = stuff.calculations(withdataa)
</code>

This gives me three lists, <code>x1</code>, <code>x2</code>, and <code>x3</code>, each of, say, size 20.

Now, I do:

<code>zipall = zip(x1, x2, x3)
</code>

However, when I do:

<code>print ""len of zipall %s"" % len(zipall)
</code>

I get 20, which is not what I expected. I expected three. I think I am doing something fundamentally wrong.
"
13890935|"Does Python's time.time() return the local or UTC timestamp?"|"Does <code>time.time()</code> in the Python time module return the system's time or the time in UTC?
"
14149422|"Using pip behind a proxy"|"I'm trying to use pip behind a proxy at work. I'm not a networking expert so bear with me if this super obvious.

One of the answers from this post suggested using CNTLM. I installed and configured it per this other post, but running <code>cntlm.exe -c cntlm.ini -I -M http://google.com</code> gave the error <code>Connection to proxy failed, bailing out</code>.

I also tried <code>pip install -–proxy=user:pass@localhost:3128</code> (the default CNTLM port) but that raised <code>Cannot fetch index base URL http://pypi.python.org/simple/</code>. Clearly something's up with the proxy.

Does anyone know how to check more definitively whether CNTLM is set up right, or if there's another way around this altogether? I know you can also set the <code>http_proxy</code> environment variable as described here but I'm not sure what credentials to put in. The ones from <code>cntlm.ini</code>?

Thanks!
"
14261614|"How do I install the yaml package for Python?"|"I have a Python program that uses YAML.  I attempted to install it on a new server using <code>pip install yaml</code> and it returns the following:

<code>$ sudo pip install yaml
Downloading/unpacking yaml
  Could not find any downloads that satisfy the requirement yaml
No distributions at all found for yaml
Storing complete log in /home/pa/.pip/pip.log
</code>

How do I install the yaml package for Python?  I'm running Python 2.7.
"
14507591|"Python Dictionary Comprehension"|"Is it possible to create a dictionary comprehension in Python (for the keys)?

Without list comprehensions, you can use something like this:

<code>l = []
for n in range(1, 11):
    l.append(n)
</code>

We can shorten this to a list comprehension: <code>l = [n for n in range(1, 11)]</code>.

However, say I want to set a dictionary's keys to the same value.
I can do:

<code>d = {}
for n in range(1, 11):
     d[n] = True # same value for each
</code>

I've tried this:

<code>d = {}
d[i for i in range(1, 11)] = True
</code>

However, I get a <code>SyntaxError</code> on the <code>for</code>.

In addition (I don't need this part, but just wondering), can you set a dictionary's keys to a bunch of different values, like this:

<code>d = {}
for n in range(1, 11):
    d[n] = n
</code>

Is this possible with a dictionary comprehension?

<code>d = {}
d[i for i in range(1, 11)] = [x for x in range(1, 11)]
</code>

This also raises a <code>SyntaxError</code> on the <code>for</code>.
"
14661701|"How to drop a list of rows from Pandas dataframe?"|"I have a dataframe df :

<code>&gt;&gt;&gt; df
                  sales  discount  net_sales    cogs
STK_ID RPT_Date                                     
600141 20060331   2.709       NaN      2.709   2.245
       20060630   6.590       NaN      6.590   5.291
       20060930  10.103       NaN     10.103   7.981
       20061231  15.915       NaN     15.915  12.686
       20070331   3.196       NaN      3.196   2.710
       20070630   7.907       NaN      7.907   6.459
</code>

Then I want to drop rows with certain sequence numbers which indicated in a list, suppose here is <code>[1,2,4],</code> then left:

<code>                  sales  discount  net_sales    cogs
STK_ID RPT_Date                                     
600141 20060331   2.709       NaN      2.709   2.245
       20061231  15.915       NaN     15.915  12.686
       20070630   7.907       NaN      7.907   6.459
</code>

How or what function can do that ?
"
14676265|"How to read text file into a list or array with Python"|"I am trying to read the lines of a text file into a list or array in python.  I just need to be able to individually access any item in the list or array after it is created.

The text file is formatted as follows:

<code>0,0,200,0,53,1,0,255,...,0.
</code>

Where the <code>...</code> is above, there actual text file has hundreds or thousands more items.

I'm using the following code to try to read the file into a list:

<code>text_file = open(""filename.dat"", ""r"")
lines = text_file.readlines()
print lines
print len(lines)
text_file.close()
</code>

The output I get is:

<code>['0,0,200,0,53,1,0,255,...,0.']
1
</code>

Apparently it is reading the entire file into a list of just one item, rather than a list of individual items.  What am I doing wrong?
"
14693646|"Writing to CSV with Python adds blank lines"|"I am trying to write to CSV file but there are blank rows in between. How can I remove the blank rows?

<code>import csv
b = open('test.csv', 'w')
a = csv.writer(b)
data = [['Me', 'You'],\
        ['293', '219'],\
        ['54', '13']]
a.writerows(data)
b.close()
</code>
"
15221473|"How do I update pip itself from inside my virtual environment?"|"I'm able to update pip-managed packages, but how do I update pip itself? According to <code>pip --version</code>, I currently have pip 1.1 installed in my virtualenv and I want to update to the latest version. 

What's the command for that? Do I need to use distribute or is there a native pip or virtualenv command? I've already tried <code>pip update</code> and <code>pip update pip</code> with no success.
"
15286401|"Print multiple arguments in python"|"This is just a snippet of my code:

<code>print(""Total score for %s is %s  "", name, score)
</code>

but I want it to print out:
""Total score for (name) is (score)"" where name is a variable in a list and score is an integer. This is python 3.3 if that helps at all. 
"
15769246|"Pythonic way to print list items"|"I would like to know if there is a better way to print all objects in a Python list than this :

<code>myList = [Person(""Foo""), Person(""Bar"")]
print(""\n"".join(map(str, myList)))
Foo
Bar
</code>

I read this way is not really good :

<code>myList = [Person(""Foo""), Person(""Bar"")]
for p in myList:
    print(p)
</code>

Isn't there something like :

<code>print(p) for p in myList
</code>

If not, my question is... why ? If we can do this kind of stuff with comprehensive lists, why not as a simple statement outside a list ?
"
15785719|"How to print a dictionary line by line in Python?"|"This is the dictionary

<code>cars = {'A':{'speed':70,
        'color':2},
        'B':{'speed':60,
        'color':3}}
</code>

Using this <code>for loop</code>

<code>for keys,values in cars.items():
    print(keys)
    print(values)
</code>

It prints the following:

<code>B
{'color': 3, 'speed': 60}
A
{'color': 2, 'speed': 70}
</code>

But I want the program to print it like this:

<code>B
color : 3
speed : 60
A
color : 2
speed : 70
</code>

I just started learning dictionaries so I'm not sure how to do this.
"
15891038|"Pandas: change data type of columns"|"I want to convert a table, represented as a list of lists, into a Pandas DataFrame. As an extremely simplified example:

<code>a = [['a', '1.2', '4.2'], ['b', '70', '0.03'], ['x', '5', '0']]
df = pd.DataFrame(a)
</code>

What is the best way to convert the columns to the appropriate types, in this case columns 2 and 3 into floats? Is there a way to specify the types while converting to DataFrame? Or is it better to create the DataFrame first and then loop through the columns to change the type for each column? Ideally I would like to do this in a dynamic way because there can be hundreds of columns and I don't want to specify exactly which columns are of which type. All I can guarantee is that each columns contains values of the same type.
"
15943769|"How do I get the row count of a Pandas dataframe?"|"I'm trying to get the number of rows of dataframe df with Pandas, and here is my code.

Method 1:

<code>total_rows = df.count
print total_rows +1
</code>

Method 2:

<code>total_rows = df['First_columnn_label'].count
print total_rows +1
</code>

Both the code snippets give me this error:


  TypeError: unsupported operand type(s) for +: 'instancemethod' and 'int'


What am I doing wrong?

According to the answer given by @root the best (the fastest) way to check df length is to call:

<code>len(df.index)
</code>
"
16296643|"Convert tuple to list and back"|"I'm currently working on a map editor for a game in pygame, using tile maps.
The level is built up out of blocks in the following structure(though much larger):

<code>level1 = (
         (1,1,1,1,1,1)
         (1,0,0,0,0,1)
         (1,0,0,0,0,1)
         (1,0,0,0,0,1)
         (1,0,0,0,0,1)
         (1,1,1,1,1,1))
</code>

where ""1"" is a block that's a wall and ""0"" is a block that's empty air.

The following code is basically the one handling the change of block type:

<code>clicked = pygame.mouse.get_pressed()
if clicked[0] == 1:
    currLevel[((mousey+cameraY)/60)][((mousex+cameraX)/60)] = 1
</code>

But since the level is stored in a tuple, I'm unable to change the values of the different blocks. How do I go about changing the different values in the level in an easy manner?

Edit: Solved! Thank you guys
"
16476924|"How to iterate over rows in a DataFrame in Pandas?"|"I have a DataFrames from pandas:

<code>import pandas as pd
inp = [{'c1':10, 'c2':100}, {'c1':11,'c2':110}, {'c1':12,'c2':120}]
df = pd.DataFrame(inp)
print df
</code>

Output:

<code>   c1   c2
0  10  100
1  11  110
2  12  120
</code>

Now I want to iterate over the rows of the above frame. For every row I want to be able to access its elements (values in cells) by the name of the columns. So, for example, I would like to have something like that:

<code>for row in df.rows:
   print row['c1'], row['c2']
</code>

Is it possible to do that in pandas?

I found similar question. But it does not give me the answer I need. For example, it is suggested there to use:

<code>for date, row in df.T.iteritems():
</code>

or

<code>for row in df.iterrows():
</code>

But I do not understand what the <code>row</code> object is and how I can work with it.
"
16503560|"Read specific columns from a csv file with csv module?"|"I'm trying to parse through a csv file and extract the data from only specific columns.

Example csv:

<code>ID | Name | Address | City | State | Zip | Phone | OPEID | IPEDS |
10 | C... | 130 W.. | Mo.. | AL... | 3.. | 334.. | 01023 | 10063 |
</code>

I'm trying to capture only specific columns, say <code>ID</code>, <code>Name</code>, <code>Zip</code> and <code>Phone</code>.

Code I've looked at has led me to believe I can call the specific column by its corresponding number, so ie: <code>Name</code> would correspond to <code>2</code> and iterating through each row using <code>row[2]</code> would produce all the items in column 2. Only it doesn't.

Here's what I've done so far:

<code>import sys, argparse, csv
from settings import *

# command arguments
parser = argparse.ArgumentParser(description='csv to postgres',\
 fromfile_prefix_chars=""@"" )
parser.add_argument('file', help='csv file to import', action='store')
args = parser.parse_args()
csv_file = args.file

# open csv file
with open(csv_file, 'rb') as csvfile:

    # get number of columns
    for line in csvfile.readlines():
        array = line.split(',')
        first_item = array[0]

    num_columns = len(array)
    csvfile.seek(0)

    reader = csv.reader(csvfile, delimiter=' ')
        included_cols = [1, 2, 6, 7]

    for row in reader:
            content = list(row[i] for i in included_cols)
            print content
</code>

and I'm expecting that this will print out only the specific columns I want for each row except it doesn't, I get the last column only.
"
16720541|"Python string.replace regular expression"|"I have a parameter file of the form

<code>parameter-name parameter-value
</code>

where the parameters may be in any order but there is only one parameter per line.  I want to replace one parameter's parameter-value with a new value.

I am using a line replace function posted previously (Search and replace a line in a file in Python) to replace the line which uses python's string.replace(pattern, subst).  The regular expression that I'm using works for instance in vim but doesn't appear to work in string.replace.  Here is the regular expression that I'm using:

<code>line.replace(""^.*interfaceOpDataFile.*$/i"", ""interfaceOpDataFile %s"" % (fileIn))
</code>

where interfaceOpDataFile is the parameter name that I'm replacing (/i for case insensitive) and the new parameter value is the contents of the fileIn variable.  Is there a way to get python to recognize this regular expression or else is there another way to accomplish this task?  Thanks in advance.
"
16819222|"How to return dictionary keys as a list in Python"|"I have noticed a difference in Python 2.7 and old versions of Python 3 compared to Python >= 3.3.



Previously in Python 2.7, I could get dictionary keys, values, or items as a list:

<code>&gt;&gt;&gt; newdict = {1:0, 2:0, 3:0}
&gt;&gt;&gt; newdict.keys()
[1, 2, 3]
</code>

Now in Python >= 3.3 I get something this:

<code>&gt;&gt;&gt; newdict.keys()
dict_keys([1, 2, 3])
</code>

So I have to do this to get a list:

<code>newlist = list()
for i in newdict.keys():
    newlist.append(i)
</code>



I am wondering if there is a better way to return a list in Python 3? 
"
16923281|"Pandas writing dataframe to CSV file"|"I have a dataframe in pandas which I would like to write to a CSV file. I am doing this using:

<code>df.to_csv('out.csv')
</code>

And getting the error:

<code>UnicodeEncodeError: 'ascii' codec can't encode character u'\u03b1' in position 20: ordinal not in range(128)
</code>

Is there any way to get around this easily (i.e. I have unicode characters in my data frame)? And is there a way to write to a tab delimited file instead of a CSV using e.g. a 'to-tab' method (that I dont think exists)?
"
17071871|"Select rows from a DataFrame based on values in a column in pandas"|"How to select rows from a DataFrame based on values in some column in pandas?
In SQL I would use: 

<code>select * from table where colume_name = some_value. 
</code>

I tried to look at pandas documentation but did not immediately find the answer.
"
17140886|"How to search and replace text in a file using Python?"|"How do I search and replace text in a file using Python 3?

Here is my code:

<code>import os
import sys
import fileinput

print (""Text to search for:"")
textToSearch = input( ""&gt; "" ) 

print (""Text to replace it with:"")
textToReplace = input( ""&gt; "" )

print (""File to perform Search-Replace on:"")
fileToSearch  = input( ""&gt; "" )
#fileToSearch = 'D:\dummy1.txt'

tempFile = open( fileToSearch, 'r+' )

for line in fileinput.input( fileToSearch ):
    if textToSearch in line :
        print('Match Found')
    else:
        print('Match Not Found!!')
    tempFile.write( line.replace( textToSearch, textToReplace ) )
tempFile.close()


input( '\n\n Press Enter to exit...' )
</code>

Input file:


  hi this is abcd hi this is abcd
  
  This is dummy text file.
  
  This is how search and replace works abcd


When I search and replace 'ram' by 'abcd' in above input file, it works as a charm. But when I do vice-verse i.e. 'abcd' by 'ram', some junk characters are left at the end.

Replacing 'abcd' by 'ram'


  hi this is ram hi this is ram
  
  This is dummy text file.
  
  This is how search and replace works ram

"
17153779|"How can I print variable and string on same line in Python?"|"I am using python to work out how many children would be born in 5 years if a child was born every 7 seconds. The problem is on my last line. How do I get a variable to work when I'm printing text either side of it? 

Here is my code:

<code>currentPop = 312032486
oneYear = 365
hours = 24
minutes = 60
seconds = 60

# seconds in a single day
secondsInDay = hours * minutes * seconds

# seconds in a year
secondsInYear = secondsInDay * oneYear

fiveYears = secondsInYear * 5

#Seconds in 5 years
print fiveYears

# fiveYears in seconds, divided by 7 seconds
births = fiveYears // 7

print ""If there was a birth every 7 seconds, there would be: "" births ""births""
</code>
"
17271319|"How do I install pip on macOS or OS X?"|"I spent most of the day yesterday searching for a clear answer for installing <code>pip</code> (package manager for Python). I can't find a good solution.

How do I install it?
"
17309288|"ImportError: No module named requests"|"Whenever I run this code, I consistently get an error saying <code>No module Named requests</code>:

<code>import requests
</code>

The error I get:

<code> File ""ex2.py"", line 1, in &lt;module&gt;
    import requests
ImportError: No module named requests
</code>
"
17330160|"How does the @property decorator work?"|"I would like to understand how the built-in function <code>property</code> works. What confuses me is that <code>property</code> can also be used as a decorator, but it only takes arguments when used as a built-in function and not when used as a decorator.

This example is from the documentation:

<code>class C(object):
    def __init__(self):
        self._x = None

    def getx(self):
        return self._x
    def setx(self, value):
        self._x = value
    def delx(self):
        del self._x
    x = property(getx, setx, delx, ""I'm the 'x' property."")
</code>

<code>property</code>'s arguments are <code>getx</code>, <code>setx</code>, <code>delx</code> and a doc string.

In the code below <code>property</code> is used as decorator. The object of it is the <code>x</code> function, but in the code above there is no place for an object function in the arguments.

<code>class C(object):
    def __init__(self):
        self._x = None

    @property
    def x(self):
        """"""I'm the 'x' property.""""""
        return self._x

    @x.setter
    def x(self, value):
        self._x = value

    @x.deleter
    def x(self):
        del self._x
</code>

And, how are the <code>x.setter</code> and <code>x.deleter</code> decorators created?
I am confused.
"
17886647|"Can't install via pip because of egg_info error"|"No matter which package I'm trying to install, I get this error: 

<code>error: invalid command 'egg_info'

----------------------------------------
Cleaning up...
Command python setup.py egg_info failed with error code 1 in c:\users\zorpix\appdata\local\temp\pip-build-Zorpix\virtualenv
Storing complete log in C:\Users\Zorpix\pip\pip.log
</code>

I saw this question, but the answer doesn't work for me. I can install the distribute package, which so far is the only package I can install, but it doesn't fix the problem, as the egg_info error returns as soon as I try to install another package. I'm getting pretty frustrated with this, as I can't find anything helpful anywhere. I've also had django and pip and everything installed before, but I had to reinstall it all, and now it's not working... Any help would be appreciated.

Here is the log it says it stored:

<code>------------------------------------------------------------
C:\Python27\Scripts\pip-script.py run on 07/26/13 11:30:42
Downloading/unpacking virtualenv

  Getting page https://pypi.python.org/simple/virtualenv/
  URLs to search for versions for virtualenv:
  * https://pypi.python.org/simple/virtualenv/
  Analyzing links from page https://pypi.python.org/simple/virtualenv/
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.3.tar.gz#md5=36b766604542f2c34d8dffdb21ba14a9 (from https://pypi.python.org/simple/virtualenv/), version: 1.3
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.6.2.tar.gz#md5=e948af53ad41ca2718c4034484fcd694 (from https://pypi.python.org/simple/virtualenv/), version: 1.6.2
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.7.tar.gz#md5=dcc105e5a3907a9dcaa978f813a4f526 (from https://pypi.python.org/simple/virtualenv/), version: 1.7
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.3.2-py2.4.egg#md5=6913c03f02167fe4ac32add76c3edeb7 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.9.tar.gz#md5=c49067cab242b5ff8c7b681a5a99533a (from https://pypi.python.org/simple/virtualenv/), version: 1.4.9
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.8.tar.gz#md5=88c187a93a78c4c9bd54eef9ef0e0f03 (from https://pypi.python.org/simple/virtualenv/), version: 0.8
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.9.1-py2.4.egg#md5=f595300f14597da25feabaececcf62a2 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.6.3.tar.gz#md5=73a69184e35f1e2c2f9016c889c4d26a (from https://pypi.python.org/simple/virtualenv/), version: 1.6.3
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.8.3.tar.gz#md5=d635fb7de359ff603a1fc395933724d1 (from https://pypi.python.org/simple/virtualenv/), version: 0.8.3
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.8.3.tar.gz#md5=d42ab84b1b38258f2a57365841186f71 (from https://pypi.python.org/simple/virtualenv/), version: 1.8.3
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.3.1.tar.gz#md5=e70ed86cc3823f0b622e80e035b59297 (from https://pypi.python.org/simple/virtualenv/), version: 1.3.1
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.5.tar.gz#md5=a8c756de9661323b1f95311e79f8a5f3 (from https://pypi.python.org/simple/virtualenv/), version: 1.5
    Skipping link https://pypi.python.org/packages/2.6/v/virtualenv/virtualenv-1.3.4-py2.6.egg#md5=f5cf3d4dba3a224351fb5f90f59dae1a (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.3-py2.4.egg#md5=ff872f8b8dcb3dc76d9c2793afc9b1a5 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.8.3-py2.4.egg#md5=fbcb29d72e35ee93d80738d46e69d350 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.3.4-py2.5.egg#md5=2fd8f371cc83c2a49009e5fe51fcd9c9 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.0.tar.gz#md5=fb86aabdfc2033612b936cf08ad811ec (from https://pypi.python.org/simple/virtualenv/), version: 1.0
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.8.3-py2.5.egg#md5=7592e9dd19388a037768840caac00255 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.3.1-py2.5.egg#md5=f042320f7301a77311b876ed55d2a635 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.7.1.tar.gz#md5=1a07359ff6e5dbfaefa6381516293b47 (from https://pypi.python.org/simple/virtualenv/), version: 1.7.1
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.3.3-py2.4.egg#md5=9cd8f513ba25e09be54ead5b1325ad3e (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.2-py2.5.egg#md5=0043570e1c16af8d3c9fa1e99bce012b (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.3.3.tar.gz#md5=28e2955aed4ffc4dc3df02dc632b5c42 (from https://pypi.python.org/simple/virtualenv/), version: 1.3.3
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.8.1-py2.4.egg#md5=fa8831295f1073151876375c4567f5cd (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.7.1.1.tar.gz#md5=e06efff3c3dd5f88758dde29e108bfdd (from https://pypi.python.org/simple/virtualenv/), version: 1.7.1.1
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.tar.gz#md5=ef70dc53c648f4253335351c65b5740f (from https://pypi.python.org/simple/virtualenv/), version: 1.4
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4rc1.tar.gz#md5=fb62a93b054e877e6a6c92f7dcd0b6ae (from https://pypi.python.org/simple/virtualenv/), version: 1.4rc1
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.8.4.tar.gz#md5=30f053782cc29363927b848263ae9158 (from https://pypi.python.org/simple/virtualenv/), version: 0.8.4
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.9.2-py2.4.egg#md5=319b534ed28e2d31b124b1a76f42fbc7 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.9.2-py2.5.egg#md5=7a4d37d0c3f83f917d7a6556f31bb31d (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.8.2-py2.5.egg#md5=eedbc037902cd2010b055451641addcf (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.3.2.tar.gz#md5=a013d5a7d9aeddc16bee88604d6de636 (from https://pypi.python.org/simple/virtualenv/), version: 1.3.2
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.9.tar.gz#md5=17a52f8801cbeb6805f4a4650dc89468 (from https://pypi.python.org/simple/virtualenv/), version: 0.9
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.0-py2.5.egg#md5=e6881a6353543b0af8b116ed8ed2f6f6 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.9.2.tar.gz#md5=78b6e73600db0d5ed8c0e507f0f7d705 (from https://pypi.python.org/simple/virtualenv/), version: 0.9.2
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.8.1-py2.5.egg#md5=ad5869374196f7d533a9b649adfe9014 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.8.tar.gz#md5=74ded4025a56e538c1c8df6b9825a8b8 (from https://pypi.python.org/simple/virtualenv/), version: 1.4.8
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.9.1.tar.gz#md5=d9abf1dc9dcaf603c60840c582414f66 (from https://pypi.python.org/simple/virtualenv/), version: 0.9.1
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.3.4-py2.4.egg#md5=bd62418a72b7e09a637ef368b7b0101b (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.5.tar.gz#md5=d3c621dd9797789fef78442e336df63e (from https://pypi.python.org/simple/virtualenv/), version: 1.4.5
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.6.tar.gz#md5=b1c585e0bbe4fca56bfa0b34aff87bd9 (from https://pypi.python.org/simple/virtualenv/), version: 1.6
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.8.2.tar.gz#md5=241f157e92dd9052b5a4b43efcef8035 (from https://pypi.python.org/simple/virtualenv/), version: 0.8.2
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.3.1-py2.4.egg#md5=708cc5281dae7fdd8d996cdb55bef52d (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.8.2-py2.4.egg#md5=4a92b99c93026031b7298906bf126ccd (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.1.tar.gz#md5=6ab218532376c2a389ef4ea030ff96f2 (from https://pypi.python.org/simple/virtualenv/), version: 1.4.1
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.3.3-py2.5.egg#md5=fae350c941cd9eadf5e9a407c37a2e03 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.8.tar.gz#md5=fdab30066a1d731ca6fe22a4c23b9e80 (from https://pypi.python.org/simple/virtualenv/), version: 1.8
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.3.4.tar.gz#md5=77d675df104b90fceec749150bd5014f (from https://pypi.python.org/simple/virtualenv/), version: 1.3.4
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.2.tar.gz#md5=7b1a10f0e84dd945c9b006ace1e1bb16 (from https://pypi.python.org/simple/virtualenv/), version: 1.4.2
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.8.4-py2.4.egg#md5=6d2db4c08a9b8a7b59e1ab7731791381 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-0.9-py2.4.egg#md5=12b34ae909f578910c293ecfe7c793e3 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.6.tar.gz#md5=f576969d591a054132fe8c9165c2b3c3 (from https://pypi.python.org/simple/virtualenv/), version: 1.4.6
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-0.8.1.tar.gz#md5=5d7b4784f530bd8acf44b568776dbd3c (from https://pypi.python.org/simple/virtualenv/), version: 0.8.1
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.3.tar.gz#md5=2b639cee32d15fd049a49561957afe4b (from https://pypi.python.org/simple/virtualenv/), version: 1.4.3
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.8.4-py2.5.egg#md5=40300b786dad2e8380ef785c4998f421 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.0-py2.4.egg#md5=6199b281bf6e7370d896520eb3a968f8 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.2.tar.gz#md5=7ad454e52f025cad631d03331ade4aaf (from https://pypi.python.org/simple/virtualenv/), version: 1.2
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.2-py2.4.egg#md5=53ab95a286cc0382e503306bb0df9d49 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.5.2.tar.gz#md5=fbcefbd8520bb64bc24a560c6019a73c (from https://pypi.python.org/simple/virtualenv/), version: 1.5.2
    Skipping link https://pypi.python.org/packages/2.4/v/virtualenv/virtualenv-1.1-py2.4.egg#md5=d9b0de14426957e30b2aa7015451aa43 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.4.7-py2.5.egg#md5=e1bb0e1cbc4e2df64dfdde6b0867ef29 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.8.2.tar.gz#md5=174ca075c6b1a42c685415692ec4ce2e (from https://pypi.python.org/simple/virtualenv/), version: 1.8.2
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.6.1.tar.gz#md5=1a475df2219457b6b4febb9fe595d915 (from https://pypi.python.org/simple/virtualenv/), version: 1.6.1
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.5.1.tar.gz#md5=3daa1f449d5d2ee03099484cecb1c2b7 (from https://pypi.python.org/simple/virtualenv/), version: 1.5.1
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.4.tar.gz#md5=94161ae1500cb3a8b003c0c394c9dbbd (from https://pypi.python.org/simple/virtualenv/), version: 1.4.4
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.7.tar.gz#md5=979a7adf8467df7df800a45debd2074f (from https://pypi.python.org/simple/virtualenv/), version: 1.4.7
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.7.2.tar.gz#md5=b5d63b05373a4344ae099a68875aae78 (from https://pypi.python.org/simple/virtualenv/), version: 1.7.2
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.8.4.tar.gz#md5=1c7e56a7f895b2e71558f96e365ee7a7 (from https://pypi.python.org/simple/virtualenv/), version: 1.8.4
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.7.1.2.tar.gz#md5=3be8a014c27340f48b56465f9109d9fa (from https://pypi.python.org/simple/virtualenv/), version: 1.7.1.2
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.9.tar.gz#md5=e03b76752b8ce7eee67c6298414cac79 (from https://pypi.python.org/simple/virtualenv/), version: 1.9
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.8.1.tar.gz#md5=3aebe32859aa4512e1e679834c10f7bf (from https://pypi.python.org/simple/virtualenv/), version: 1.8.1
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.9.1-py2.5.egg#md5=573b8bd74a7b9b207b5eede8db386953 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.1.tar.gz#md5=8931b66dbb799120583dd107aab2fa89 (from https://pypi.python.org/simple/virtualenv/), version: 1.1
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.3-py2.5.egg#md5=8102d251e3f1caf709722679a737f454 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.1-py2.5.egg#md5=1db8cdd823739c79330a138327239551 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.6.4.tar.gz#md5=1072b66d53c24e019a8f1304ac9d9fc5 (from https://pypi.python.org/simple/virtualenv/), version: 1.6.4
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-1.3.2-py2.5.egg#md5=f2cd2b10b8be8b57e74cb1830fc0b504 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Skipping link https://pypi.python.org/packages/2.5/v/virtualenv/virtualenv-0.9-py2.5.egg#md5=7c8e85680f1ede0844a496513366d7a5 (from https://pypi.python.org/simple/virtualenv/); unknown archive format: .egg
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.10.tar.gz#md5=9745c28256c70c76d36adb3767a00212 (from https://pypi.python.org/simple/virtualenv/), version: 1.10
    Found link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.9.1.tar.gz#md5=07e09df0adfca0b2d487e39a4bf2270a (from https://pypi.python.org/simple/virtualenv/), version: 1.9.1
  Ignoring link https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4rc1.tar.gz#md5=fb62a93b054e877e6a6c92f7dcd0b6ae (from https://pypi.python.org/simple/virtualenv/), version 1.4rc1 is a pre-release (use --pre to allow).
  Using version 1.10 (newest of versions: 1.10, 1.9.1, 1.9, 1.8.4, 1.8.3, 1.8.2, 1.8.1, 1.8, 1.7.2, 1.7.1.2, 1.7.1.1, 1.7.1, 1.7, 1.6.4, 1.6.3, 1.6.2, 1.6.1, 1.6, 1.5.2, 1.5.1, 1.5, 1.4.9, 1.4.8, 1.4.7, 1.4.6, 1.4.5, 1.4.4, 1.4.3, 1.4.2, 1.4.1, 1.4, 1.3.4, 1.3.3, 1.3.2, 1.3.1, 1.3, 1.2, 1.1, 1.0, 0.9.2, 0.9.1, 0.9, 0.8.4, 0.8.3, 0.8.2, 0.8.1, 0.8)
  Downloading from URL https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.10.tar.gz#md5=9745c28256c70c76d36adb3767a00212 (from https://pypi.python.org/simple/virtualenv/)
  Running setup.py egg_info for package virtualenv

    C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'entry_points'

      warnings.warn(msg)

    C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'zip_safe'

      warnings.warn(msg)

    C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'test_suite'

      warnings.warn(msg)

    C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'tests_require'

      warnings.warn(msg)

    usage: -c [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]

       or: -c --help [cmd1 cmd2 ...]

       or: -c --help-commands

       or: -c cmd --help



    error: invalid command 'egg_info'

    Complete output from command python setup.py egg_info:

    C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'entry_points'

  warnings.warn(msg)

C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'zip_safe'

  warnings.warn(msg)

C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'test_suite'

  warnings.warn(msg)

C:\Python27\lib\distutils\dist.py:267: UserWarning: Unknown distribution option: 'tests_require'

  warnings.warn(msg)

usage: -c [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]

   or: -c --help [cmd1 cmd2 ...]

   or: -c --help-commands

   or: -c cmd --help



error: invalid command 'egg_info'

----------------------------------------

Cleaning up...

  Removing temporary dir c:\users\joey\appdata\local\temp\pip-build-Joey...
Command python setup.py egg_info failed with error code 1 in c:\users\joey\appdata\local\temp\pip-build-Joey\virtualenv

Exception information:
Traceback (most recent call last):
  File ""C:\Python27\lib\site-packages\pip\basecommand.py"", line 134, in main
    status = self.run(options, args)
  File ""C:\Python27\lib\site-packages\pip\commands\install.py"", line 236, in run
    requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File ""C:\Python27\lib\site-packages\pip\req.py"", line 1124, in prepare_files
    req_to_install.run_egg_info()
  File ""C:\Python27\lib\site-packages\pip\req.py"", line 257, in run_egg_info
    command_desc='python setup.py egg_info')
  File ""C:\Python27\lib\site-packages\pip\util.py"", line 670, in call_subprocess
    % (command_desc, proc.returncode, cwd))
InstallationError: Command python setup.py egg_info failed with error code 1 in c:\users\joey\appdata\local\temp\pip-build-Joey\virtualenv
</code>

EDIT:
Not sure what I did, but now I'm getting this error:

<code>ImportError: No module named setuptools.command

----------------------------------------
Cleaning up...
Command python setup.py egg_info failed with error code 1 in c:\users\joey\appdata\local\temp\pip-build-Joey\Django
Storing complete log in C:\Users\Joey\pip\pip.log
</code>

What is this setuptools that I'm missing?
"
18053500|"TypeError: not all arguments converted during string formatting python"|"The program is supposed to take in two names, and if they are the same length it should check if they are the same word.  If it's the same word it will print ""The names are the same"". If they are the same length but with different letters it will print ""The names are different but the same length"". The part I'm having a problem with is in the bottom 4 lines.

<code>#!/usr/bin/env python
# Enter your code for ""What's In (The Length Of) A Name?"" here.
name1 = input(""Enter name 1: "")
name2 = input(""Enter name 2: "")
len(name1)
len(name2)
if len(name1) == len(name2):
    if name1 == name2:
        print (""The names are the same"")
    else:
        print (""The names are different, but are the same length"")
    if len(name1) &gt; len(name2):
        print (""'{0}' is longer than '{1}'""% name1, name2)
    elif len(name1) &lt; len(name2):
        print (""'{0}'is longer than '{1}'""% name2, name1)
</code>

When I run this code it displays:

<code>Traceback (most recent call last):
  File ""program.py"", line 13, in &lt;module&gt;
    print (""'{0}' is longer than '{1}'""% name1, name2)
TypeError: not all arguments converted during string formatting
</code>

Any suggestions are highly appreciated.
"
18172851|"Deleting DataFrame row in Pandas based on column value"|"I have the following DataFrame:

<code>             daysago  line_race rating        rw    wrating
 line_date                                                 
 2007-03-31       62         11     56  1.000000  56.000000
 2007-03-10       83         11     67  1.000000  67.000000
 2007-02-10      111          9     66  1.000000  66.000000
 2007-01-13      139         10     83  0.880678  73.096278
 2006-12-23      160         10     88  0.793033  69.786942
 2006-11-09      204          9     52  0.636655  33.106077
 2006-10-22      222          8     66  0.581946  38.408408
 2006-09-29      245          9     70  0.518825  36.317752
 2006-09-16      258         11     68  0.486226  33.063381
 2006-08-30      275          8     72  0.446667  32.160051
 2006-02-11      475          5     65  0.164591  10.698423
 2006-01-13      504          0     70  0.142409   9.968634
 2006-01-02      515          0     64  0.134800   8.627219
 2005-12-06      542          0     70  0.117803   8.246238
 2005-11-29      549          0     70  0.113758   7.963072
 2005-11-22      556          0     -1  0.109852  -0.109852
 2005-11-01      577          0     -1  0.098919  -0.098919
 2005-10-20      589          0     -1  0.093168  -0.093168
 2005-09-27      612          0     -1  0.083063  -0.083063
 2005-09-07      632          0     -1  0.075171  -0.075171
 2005-06-12      719          0     69  0.048690   3.359623
 2005-05-29      733          0     -1  0.045404  -0.045404
 2005-05-02      760          0     -1  0.039679  -0.039679
 2005-04-02      790          0     -1  0.034160  -0.034160
 2005-03-13      810          0     -1  0.030915  -0.030915
 2004-11-09      934          0     -1  0.016647  -0.016647
</code>

I need to remove the rows where <code>line_race</code> is equal to <code>0</code>. What's the most efficient way to do this?
"
18265935|"Python - Create list with numbers between 2 values?"|"How would I create a list with values between 2 values I put in? 
For example, following list is generated for values between 11 and 16:

<code>list = [11, 12, 13, 14, 15, 16]
</code>
"
18533621|"Error when creating a new text file with python?"|"This function doesn't work and raises an error. Do I need to change any arguments or parameters?  

<code>import sys

def write():
    print('Creating new text file') 

    name = input('Enter name of text file: ')+'.txt'  # Name of text file coerced with +.txt

    try:
        file = open(name,'r+')   # Trying to create a new file or open one
        file.close()

    except:
        print('Something went wrong! Can\'t tell what?')
        sys.exit(0) # quit Python

write()
</code>
"
19019720|"ImportError: DLL load failed: %1 is not a valid Win32 application. But the DLL's are there"|"I have a situation very much like the one at ImportError: DLL load failed: %1 is not a valid Win32 application, but the answer there isn't working for me.

My Python code says:

<code>import cv2
</code>

But that line throws the error shown in the title of this question.

I have OpenCV installed in <code>C:\lib\opencv</code> on this 64-bit machine. I'm using 64-bit Python.

My PYTHONPATH variable: <code>PYTHONPATH=C:\lib\opencv\build\python\2.7</code>. This folder contains <code>cv2.pyd</code> and that's all.

My PATH variable: <code>Path=%OPENCV_DIR%\bin;...</code> This folder contains 39 DLL files such as <code>opencv_core246d.dll</code>.

OPENCV_DIR has this value: <code>OPENCV_DIR=C:\lib\opencv\build\x64\vc11</code>.

The solution at ImportError: DLL load failed: %1 is not a valid Win32 application says to add ""the new opencv binaries path (<code>C:\opencv\build\bin\Release</code>) to the Windows PATH environment variable"". But as shown above, I already have the OpenCV binaries folder (<code>C:\lib\opencv\build\x64\vc11\bin</code>) in my PATH. And my OpenCV installation doesn't have any Release folders (except for an empty one under build/java).

Any ideas as to what's going wrong? Can I tell Python to verbosely trace the loading process? Exactly what DLL's is it looking for?

Thanks,
Lars

EDIT:

I just noticed that, according to http://www.dependencywalker.com/, the <code>cv2.pyd</code> in <code>C:\lib\opencv\build\python\2.7</code> is 32-bit, whereas the machine and the Python I'm running are 64-bit. Could that be the problem? And if so, where can I find a 64-bit version of cv2.pyd?
"
19410042|"How to make IPython notebook matplotlib plot inline"|"I am trying to use IPython notebook on MacOS X with Python 2.7.2 and IPython 1.1.0.

I cannot get matplotlib graphics to show up inline.

<code>import matplotlib
import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline  
</code>

I have also tried <code>%pylab inline</code> and the ipython command line arguments <code>--pylab=inline</code> but this makes no difference.

<code>x = np.linspace(0, 3*np.pi, 500)
plt.plot(x, np.sin(x**2))
plt.title('A simple chirp')
plt.show()
</code>

Instead of inline graphics, I get this:

<code>&lt;matplotlib.figure.Figure at 0x110b9c450&gt;
</code>

And <code>matplotlib.get_backend()</code> shows that I have the <code>'module://IPython.kernel.zmq.pylab.backend_inline'</code> backend.
"
19482970|"Get list from pandas DataFrame column headers"|"I want to get a list of the column headers from a pandas DataFrame.  The DataFrame will come from user input so I won't know how many columns there will be or what they will be called.

For example, if I'm given a DataFrame like this:

<code>&gt;&gt;&gt; my_dataframe
    y  gdp  cap
0   1    2    5
1   2    3    9
2   8    7    2
3   3    4    7
4   6    7    7
5   4    8    3
6   8    2    8
7   9    9   10
8   6    6    4
9  10   10    7
</code>

I would want to get a list like this:

<code>&gt;&gt;&gt; header_list
[y, gdp, cap]
</code>
"
19747371|"Python exit commands - why so many and when should each be used?"|"It seems that python supports many different commands to stop script execution.The choices I've found are:  <code>quit()</code>, <code>exit()</code>, <code>sys.exit()</code>, <code>os._exit()</code> 

Have I missed any?
What's the difference between them? When would you use each?
"
20060096|"Installing PIL with pip"|"I am trying to install PIL (the Python Imaging Library) using the command:

<code>sudo pip install pil
</code>

but I get the following message:

<code>Downloading/unpacking PIL
  You are installing a potentially insecure and unverifiable file. Future versions of pip will default to disallowing insecure files.
  Downloading PIL-1.1.7.tar.gz (506kB): 506kB downloaded
  Running setup.py egg_info for package PIL
    WARNING: '' not a valid package name; please use only.-separated package names in setup.py

Installing collected packages: PIL
  Running setup.py install for PIL
    WARNING: '' not a valid package name; please use only.-separated package names in setup.py
    --- using frameworks at /System/Library/Frameworks
    building '_imaging' extension
    clang -fno-strict-aliasing -fno-common -dynamic -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -mno-fused-madd -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch x86_64 -pipe -IlibImaging -I/System/Library/Frameworks/Python.framework/Versions/2.7/include -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c _imaging.c -o build/temp.macosx-10.8-intel-2.7/_imaging.o
    unable to execute clang: No such file or directory
    error: command 'clang' failed with exit status 1
    Complete output from command /usr/bin/python -c ""import setuptools;__file__='/private/tmp/pip_build_root/PIL/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))"" install --record /tmp/pip-AYrxVD-record/install-record.txt --single-version-externally-managed:
    WARNING: '' not a valid package name; please use only.-separated package names in setup.py

running install

running build

.
.
.
.

copying PIL/XVThumbImagePlugin.py -&gt; build/lib.macosx-10.8-intel-2.7

running build_ext

--- using frameworks at /System/Library/Frameworks

building '_imaging' extension

creating build/temp.macosx-10.8-intel-2.7

creating build/temp.macosx-10.8-intel-2.7/libImaging

clang -fno-strict-aliasing -fno-common -dynamic -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -mno-fused-madd -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch x86_64 -pipe -IlibImaging -I/System/Library/Frameworks/Python.framework/Versions/2.7/include -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c _imaging.c -o build/temp.macosx-10.8-intel-2.7/_imaging.o

unable to execute clang: No such file or directory

error: command 'clang' failed with exit status 1

----------------------------------------
Cleaning up…
</code>

Could you please help me to install PIL??
"
20180543|"How to check version of python modules?"|"I just installed the python modules: <code>construct</code> and <code>statlib</code> with <code>setuptools</code> like this:

<code># Install setuptools to be able to download the following
sudo apt-get install python-setuptools

# Install statlib for lightweight statistical tools
sudo easy_install statlib

# Install construct for packing/unpacking binary data
sudo easy_install construct
</code>

I want to be able to (programmatically) check their versions.  Is there an equivalent to <code>python --version</code> I can run from the command line?

My python version is <code>2.7.3</code>.
"
20199126|"Reading JSON from a file?"|"I am getting a bit of headache just because a simple looking, easy statement is throwing some errors in my face.

I have a json file called strings.json like this:

<code>""strings"": [{""-name"": ""city"", ""#text"": ""City""}, {""-name"": ""phone"", ""#text"": ""Phone""}, ...,
            {""-name"": ""address"", ""#text"": ""Address""}]
</code>

I want to read the json file, just that for now. I have these statements which I found out, but it's not working:

<code>import json
from pprint import pprint

with open('strings.json') as json_data:
    d = json.loads(json_data)
    json_data.close()
    pprint(d)
</code>

The error displayed on the console was this:

<code>Traceback (most recent call last):
File ""/home/.../android/values/manipulate_json.py"", line 5, in &lt;module&gt;
d = json.loads(json_data)
File ""/usr/lib/python2.7/json/__init__.py"", line 326, in loads
return _default_decoder.decode(s)
File ""/usr/lib/python2.7/json/decoder.py"", line 366, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
TypeError: expected string or buffer
[Finished in 0.1s with exit code 1]
</code>

Edited

Changed from <code>json.loads</code> to <code>json.load</code>

and got this:

<code>Traceback (most recent call last):
File ""/home/.../android/values/manipulate_json.py"", line 5, in &lt;module&gt;
d = json.load(json_data)
File ""/usr/lib/python2.7/json/__init__.py"", line 278, in load
**kw)
File ""/usr/lib/python2.7/json/__init__.py"", line 326, in loads
return _default_decoder.decode(s)
File ""/usr/lib/python2.7/json/decoder.py"", line 369, in decode
raise ValueError(errmsg(""Extra data"", s, end, len(s)))
ValueError: Extra data: line 829 column 1 - line 829 column 2 (char 18476 - 18477)
[Finished in 0.1s with exit code 1]
</code>
"
20309456|"How to call a function from another file in Python?"|"I've seen this topic here covered numerous times, but none of the answers I've seen seem to work for me, so I'll try to be as specific to my problem as possible.

Set_up: I have a .py file for each function I need to use in a program. 

In this program, I need to call the function from the external files.  

I've tried:

<code>from file.py import function(a,b)
</code>

but I get the error: 

<code>ImportError: No module named 'file.py'; file is not a package
</code>
"
20449427|"How can I read inputs as integers?"|"Why does this code not input integers?  Everything on the web says to use <code>raw_input()</code>, but I read on Stack Overflow (on a thread that did not deal with integer input) that <code>raw_input()</code> was renamed to <code>input()</code> in Python 3.x.

<code>play = True

while play:

    x = input(""Enter a number: "")
    y = input(""Enter a number: "")

    print(x + y)
    print(x - y)
    print(x * y)
    print(x / y)
    print(x % y)

    if input(""Play again? "") == ""no"":
        play = False
</code>
"
20646822|"How to serve static files in Flask"|"So this is embarrassing. I've got an application that I threw together in <code>Flask</code> and for now it is just serving up a single static HTML page with some links to CSS and JS. And I can't find where in the documentation <code>Flask</code> describes returning static files. Yes, I could use <code>render_template</code> but I know the data is not templatized. I'd have thought <code>send_file</code> or <code>url_for</code> was the right thing, but I could not get those to work. In the meantime, I am opening the files, reading content, and rigging up a <code>Response</code> with appropriate mimetype:

<code>import os.path

from flask import Flask, Response


app = Flask(__name__)
app.config.from_object(__name__)


def root_dir():  # pragma: no cover
    return os.path.abspath(os.path.dirname(__file__))


def get_file(filename):  # pragma: no cover
    try:
        src = os.path.join(root_dir(), filename)
        # Figure out how flask returns static files
        # Tried:
        # - render_template
        # - send_file
        # This should not be so non-obvious
        return open(src).read()
    except IOError as exc:
        return str(exc)


@app.route('/', methods=['GET'])
def metrics():  # pragma: no cover
    content = get_file('jenkins_analytics.html')
    return Response(content, mimetype=""text/html"")


@app.route('/', defaults={'path': ''})
@app.route('/&lt;path:path&gt;')
def get_resource(path):  # pragma: no cover
    mimetypes = {
        "".css"": ""text/css"",
        "".html"": ""text/html"",
        "".js"": ""application/javascript"",
    }
    complete_path = os.path.join(root_dir(), path)
    ext = os.path.splitext(path)[1]
    mimetype = mimetypes.get(ext, ""text/html"")
    content = get_file(complete_path)
    return Response(content, mimetype=mimetype)


if __name__ == '__main__':  # pragma: no cover
    app.run(port=80)
</code>

Someone want to give a code sample or url for this? I know this is going to be dead simple.
"
21122540|"input() error - NameError: name '...' is not defined"|"I am getting an error when I try to run this simple python script:

<code>input_variable = input (""Enter your name: "")
print (""your name is"" + input_variable)
</code>

Lets say I type in ""dude"", the error I am getting is:

<code>line 1, in &lt;module&gt;
input_variable = input (""Enter your name: "")
File ""&lt;string&gt;"", line 1, in &lt;module&gt;
NameError: name 'dude' is not defined
</code>

I am running Mac OS X 10.9.1 and I am using the Python Launcher app that came with the install of python 3.3 to run the script.

Edit: I realized I am somehow running these scripts with 2.7. I guess the real question is how do I run my scripts with version 3.3? I thought if I dragged and dropped my scripts on top of the Python Launcher app that is inside the Python 3.3 folder in my applications folder that it would launch my scripts using 3.3. I guess this method still launches scripts with 2.7. So How do I use 3.3?
"
21129020|"How to fix: ""UnicodeDecodeError: 'ascii' codec can't decode byte"""|"<code>as3:~/ngokevin-site# nano content/blog/20140114_test-chinese.mkd
as3:~/ngokevin-site# wok
Traceback (most recent call last):
File ""/usr/local/bin/wok"", line 4, in
Engine()
File ""/usr/local/lib/python2.7/site-packages/wok/engine.py"", line 104, in init
self.load_pages()
File ""/usr/local/lib/python2.7/site-packages/wok/engine.py"", line 238, in load_pages
p = Page.from_file(os.path.join(root, f), self.options, self, renderer)
File ""/usr/local/lib/python2.7/site-packages/wok/page.py"", line 111, in from_file
page.meta['content'] = page.renderer.render(page.original)
File ""/usr/local/lib/python2.7/site-packages/wok/renderers.py"", line 46, in render
return markdown(plain, Markdown.plugins)
File ""/usr/local/lib/python2.7/site-packages/markdown/init.py"", line 419, in markdown
return md.convert(text)
File ""/usr/local/lib/python2.7/site-packages/markdown/init.py"", line 281, in convert
source = unicode(source)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe8 in position 1: ordinal not in range(128). -- Note: Markdown only accepts unicode input!
</code>

How to fix it?

In some other python-based static blog apps, Chinese post can be published successfully.
Such as this app: http://github.com/vrypan/bucket3. In my site http://bc3.brite.biz/, Chinese post can be published successfully.
"
21492214|"How to run Python script on terminal"|"I want to run a Python script in terminal but I don't know how? I already have saved a file called gameover.py   in /User/luca/Documents/python.
"
21530577|"fatal error: Python.h: No such file or directory"|"I am trying to build a shared library using a C extension file but first I have to generate the output file using the command below:

<code>gcc -Wall utilsmodule.c -o Utilc
</code>

After executing the command, I get this error message:


  utilsmodule.c:1:20: fatal error: Python.h: No such file or directory
  compilation terminated.


in fact I have tried all the suggested solutions over the internet but the problem still exists ... also I have no problem with <code>Python.h</code>. I managed to locate the file on my machine ... anybody has faced the same problem before??
"
21903842|"How do I compare two strings in python?"|"I have two strings like

<code>string1=""abc def ghi""
</code>

and

<code>string2=""def ghi abc""
</code>

How to get that this two string are same without breaking the words?
"
23708898|"'pip' is not recognized as an internal or external command"|"I'm running into a weird error trying to install Django on my computer.

This is the sequence that I've typed into my command line:

<code>C:\Python34&gt;python get-pip.py
Requirement already up-to-date: pip in c:\python34\lib\site-packages
Cleaning up...

C:\Python34&gt;pip install Django
'pip' is not recognized as an internal or external command,
operable program or batch file.

C:\Python34&gt;lib\site-packages\pip install Django
'lib\site-packages\pip' is not recognized as an internal or external command,
operable program or batch file. 
</code>

What could be causing this?

EDIT ___________________

As requested this is what I get when I type in echo %PATH%

<code>C:\Python34&gt;echo %PATH%
C:\Program Files\ImageMagick-6.8.8-Q16;C:\Program Files (x86)\Intel\iCLS Client\
;C:\Program Files\Intel\iCLS Client\;C:\Windows\system32;C:\Windows;C:\Windows\S
ystem32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\
Windows Live\Shared;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x86;C:\Progr
am Files (x86)\Intel\OpenCL SDK\2.0\bin\x64;C:\Program Files\Intel\Intel(R) Mana
gement Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine C
omponents\IPT;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components
\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\P
rogram Files (x86)\nodejs\;C:\Program Files (x86)\Heroku\bin;C:\Program Files (x
86)\git\cmd;C:\RailsInstaller\Ruby2.0.0\bin;C:\RailsInstaller\Git\cmd;C:\RailsIn
staller\Ruby1.9.3\bin;C:\Users\Javi\AppData\Roaming\npm
</code>
"
23842713|"Using Python 3 in virtualenv"|"Using virtualenv, I run my projects with the default version of Python (2.7). On one project, I need to use Python 3.4. 

I used <code>brew install python3</code> to install it on my Mac. Now, how do I create a virtualenv that uses the new version?

e.g. sudo virtualenv envPython3

If I try:

<code>virtualenv -p python3 test
</code>

I get:

<code>Running virtualenv with interpreter /usr/local/bin/python3
Using base prefix '/usr/local/Cellar/python3/3.4.0_1/Frameworks/Python.framework/Versions/3.4'
New python executable in test/bin/python3.4
Also creating executable in test/bin/python
Failed to import the site module
Traceback (most recent call last):
  File ""/Users/user/Documents/workspace/test/test/bin/../lib/python3.4/site.py"", line 67, in &lt;module&gt;
    import os
  File ""/Users/user/Documents/workspace/test/test/bin/../lib/python3.4/os.py"", line 634, in &lt;module&gt;
    from _collections_abc import MutableMapping
ImportError: No module named '_collections_abc'
ERROR: The executable test/bin/python3.4 is not functioning
ERROR: It thinks sys.prefix is '/Users/user/Documents/workspace/test' (should be '/Users/user/Documents/workspace/test/test')
ERROR: virtualenv is not compatible with this system or executable
</code>
"
25865270|"How to install Python MySQLdb module using pip?"|"How can I install the MySQLdb module for Python using pip?
"
26053982|"error: Setup script exited with error: command 'x86_64-linux-gnu-gcc' failed with exit status 1"|"When I try to install odoo-server I got the following error could anyone help me to resolve this?

<code>error: Setup script exited with error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
</code>
"
27341064|"How do I fix 'ImportError: cannot import name IncompleteRead'?"|"When I try to install anything with <code>pip</code> or <code>pip3</code>, I get:

<code>$ sudo pip3 install python3-tk
Traceback (most recent call last):
  File ""/usr/bin/pip3"", line 9, in &lt;module&gt;
    load_entry_point('pip==1.5.6', 'console_scripts', 'pip3')()
  File ""/usr/lib/python3/dist-packages/pkg_resources.py"", line 356, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File ""/usr/lib/python3/dist-packages/pkg_resources.py"", line 2476, in load_entry_point
    return ep.load()
  File ""/usr/lib/python3/dist-packages/pkg_resources.py"", line 2190, in load
    ['__name__'])
  File ""/usr/lib/python3/dist-packages/pip/__init__.py"", line 61, in &lt;module&gt;
    from pip.vcs import git, mercurial, subversion, bazaar  # noqa
  File ""/usr/lib/python3/dist-packages/pip/vcs/mercurial.py"", line 9, in &lt;module&gt;
    from pip.download import path_to_url
  File ""/usr/lib/python3/dist-packages/pip/download.py"", line 25, in &lt;module&gt;
    from requests.compat import IncompleteRead
ImportError: cannot import name 'IncompleteRead'
</code>

I have a Ubuntu 14.10 system.

How can I fix this problem?
"
27835619|"urllib and ""SSL: CERTIFICATE_VERIFY_FAILED"" Error"|"I am getting this error

<code>Exception in thread Thread-3:
Traceback (most recent call last):
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py"", line 810, in        __bootstrap_inner
self.run()
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py"", line 763, in  run
self.__target(*self.__args, **self.__kwargs)
File ""/Users/Matthew/Desktop/Skypebot 2.0/bot.py"", line 271, in process
info = urllib2.urlopen(req).read()
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py"", line 154, in urlopen
return opener.open(url, data, timeout)
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py"", line 431, in open
response = self._open(req, data)
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py"", line 449, in _open
'_open', req)
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py"", line 409, in _call_chain
result = func(*args)
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py"", line 1240, in https_open
context=self._context)
File ""/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py"", line 1197, in do_open
raise URLError(err)
URLError: &lt;urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:581)&gt;
</code>

This is the code that is causing this error:

<code>if input.startswith(""!web""):
    input = input.replace(""!web "", """")      
    url = ""https://domainsearch.p.mashape.com/index.php?name="" + input
    req = urllib2.Request(url, headers={ 'X-Mashape-Key': 'XXXXXXXXXXXXXXXXXXXX' })
    info = urllib2.urlopen(req).read()
    Message.Chat.SendMessage ("""" + info)
</code>

The API Im using requires me to use the https. How can I make it bypass the verification?
"
27885397|"How do I install a Python package with a .whl file?"|"I'm having trouble installing a Python package (specifically, JPype1 0.5.7) on my Windows machine, and would like to install it with Christoph Gohlke's Window binaries. (Which, to my experience, alleviated much of the fuss for many other package installations.)

However, while Christoph used to provide .exe files in the past, recently it seems he's uploading .whl files instead.

http://www.lfd.uci.edu/~gohlke/pythonlibs/#jpype

But how do I install .whl files?


  Notes:
  
  
  I've found documents on wheel, but they don't seem so staightforward in explaining how to install .whl files.
  This question is a duplicate with this question, which wasn't directly answered.
  

"