#Python ##Python CheatSheet
This python repository is prepared supposed be an online reference material. The repository has python scripting codes from beginners to advance levels. To make it accessible and more convient to use, I organized the repository in different folder structures:Variable,Expressions, Conditionals, Functions, Loops, Lists, Dictionaries and Tuples. In different folder of the repository there many python scripting codes. Codes in the Variable, Expressions, Conditionals, Functions and Loops are beginner level. The codes in the Lists, Dictionaries, Tuples and other are advanced levels. Scripting codes in the list, dictionary and tuples folder can extract large text files.It loops through each line of the file and filter the line containing emails. Then email is extracted from each lines containing email by finding and slicing method. Then email is inserted in a python list. The total emails in the file and total number of lines are counted.
##Variables, Expressions and Statements Variable are a means to store data. The data type which could be stored may be a number(int, float) or string.
#Variables containing string
name = "Python Monthy"
quest = "Scripting"
activity = "Scraping"
#To check the type of the Variables
print("name is a string",type(name))
print("quest is a string",type(quest))
print("activity is a string",type(activity))
#Variables containing numbers, integer
age = 100
year = 2017
print(age)
print(year)
#To check the type of the Variables
print("age is an int",type(age))
print("year is an int",type(year))
#variable contiaing number, float
pi = 3.14
temp = 98.6
print(pi)
print(temp)
#To check the type of the Variables
print("pi is a float",type(pi))
print("temp is a float",type(temp))
satisfied = False
hungery = False
single = True
print(satisfied)
print(single)
#To check the type of the Variables
print("satisfied is a boolean",type(satisfied))
print("single is a boolean",type(single))
#Declaring list variable in python
items = list() # this is a list
items = [] # this is also a list
print(type(items))
#Declaring list variable in python
dic = dict()
print(type(dic))Python Reserved words:
*_and del for is raise assert elif
from lambda return break else global
not try class except if or while
continue exec import pass yield
def finally in print as with_*
##Datat types
Numbers are integer(int) and decimals(float).
...-5,-4,-3,-2,-1,0,1,2,3,4,5...
age = 25
fnumber= 4
start = 0
penality = -5...-5, -5.5 ,0.25, 0, 1, 2.22, 3, 3.14..
pi = 3.14
temp = 98.6"Hello World!"
Boolean values are always true or false. It is affrimation or negation of a statement.
islighton = True
islightof = False
hungery = False
statisfied = False
married = False
student = True
print(islighton)
print(islightoff)
print(hungery)
print(married)
print(student)
Print Result:
True
False
False
False
Truex = 10
if (x > 5):
print xx = 10
if (x <5):
print(x)
else:
print(x)name =input("What is your name: ").lower()
lang = input("What language do you speak: ").lower()
if(lang == 'eng'):
print("Hello",name)
elif(lang=='es'):
print("Holla",name)
elif(lang=='fr'):
if(live =="France"):
print("Bonjour",name)
elif(lang=='fi'):
print("Moi",name)
elif(lang=='am'):
print("Selam",name)
else:
print("Do you speak English?",name)def saySomething():
print("Good Morning")name =input("What is your name: ").lower()
lang = input("What language do you speak: ").lower()
def greet(lang,name):
if(lang == 'eng'):
print("Hello",name)
elif(lang=='es'):
print("Holla",name)
elif(lang=='fr'):
print("Bonjour",name)
elif(lang=='fi'):
print("Moi",name)
elif(lang=='am'):
print("Selam",name)
else:
print("Do you speak English?",name)
greet(lang,name)sum() max() min() len()
web = ['HTML', 'CSS', 'JavaScript','Bootstrap', 'EJS','Blaze','Mustache','handlebarjs','ReactJs', 'AngularJS', 'Python', 'PHP','NodeJS','MongoDB','SQL']
for wblang in web:
print (wblang)
Print Result:
['HTML', 'CSS', 'JavaScript','Bootstrap', 'EJS','Blaze','Mustache','handlebarjs','ReactJs', 'AngularJS', 'Python', 'PHP','NodeJS','MongoDB','SQL']
#Another method to looping
for i in range(len(web)):
print(web[i])
Print Result:
['HTML', 'CSS', 'JavaScript','Bootstrap', 'EJS','Blaze','Mustache','handlebarjs','ReactJs', 'AngularJS', 'Python', 'PHP','NodeJS','MongoDB','SQL']for num in range(15):
if(num % 4 ==0):
print(num,"is divisible by f.")
Print Result:
4 is divisible by 4.
8 is divisible by 4.
12 is divisible by 4.while True:lang ="Python"
task ="scraping"
greeting = "Hello Python ninjas"
print(lang)
print(task)
print(greeting)
Print Result:
python
scraping
Hello Python ninjasgreeting = "Hello Donald J. Trump"
greeting.lower()
greeting.upper()
greeting.tittle()
greeting.endswith('g')
greeting.startswith('g')
greeting.isnumeric()methods can be found by dir(greeting) from the console
Opening file from a local disk
fname = open('file')
fhandle = fname.read()
for line fhandle:
print(line)A linear collection of values which maintain order.A list is an ordered sequence. Each value in a sequence has its own index order.
socialmedia = ['facebook','twitter','instagram', 'linkedin','pintrest','myspace'] #Fixed amount of values
lists = list() or lists = [] #Method of decalaring list variable
lists[0] = 'book'
lists[1] = 'laptop'
list[2] = 50
lists[3] = 1.5
lists[4] = 'Mango'
lists[5] = False
lists[6] = "Venomous Snake"
print(lists)
Print Result:
['book', 'laptop',50, 1.5,'Mango', False, 'Venomous Snake']lists = list()
dir(lists) # to get the list methods from consoleA data collection in which each values has its own label or key. Dictionary in python is analogous to objects in JavaScript. Dictionary doesn't maintain order.Dictionary values is looked up by their keys or labels. Dictionaries are mutable or modifiable similar to lists. However, strings are immutable. The most common use of dictionary is to count how often something can occur. Refering a key which is not in a dictionary results error.
courses = {'python':90,'javascript':95,'nodejs':85,'html':100,'css':95,'react':90,'mongodb':98}
print(courses)
shoppingbag = dict()
shoppingbag['milk'] = 2
shoppingbag['egg'] = 1
shoppingbag['coffee'] = 2
shoppingbag['sugar'] = 1.5
print(shoppingbag)
Print result:
{'python':90,'javascript':95,'nodejs':85,'html':100,'css':95,'react':90,'mongodb':98}
{'milk':2,'egg':1, 'coffee':2,'sugar':1.5} dic = dict()
print(dir(dic))Tuples like lists are a kind of sequence that users like lists. The elements of tuples are accessed by index starting from 0. Tuples are immutable like strings. Lists and dictionary are mutable(modifiable).
Example of Tuples:
countries = ('Ethiopia', 'Kenya', 'Jamaica', 'Uguanda')
countries[0] = 'Estonia' # Error, not allowed, because Tuples are immutable
print (countries[0])
print (countries[1])
print (countries[2])
print (countries[3])
for country in countries:
print (country)There are referred to as "Regex" or "regexp" Regular expressions are a concise and flexible way for matching strings of text ,characterds, words, paterns of character. A regular expression process is needed for the command to be interperated. A regular expressions are a language by themselves which can be used in other programming language too. Therefore regular expression library has to be imported to the file by using "import re" Regular Expressins:
^ Matches the beginning of a line
$ Matches the end of the line
. Matches any character
\s Matches whitespace
\S Matches any non-whitespace character
* Repeats a character zero or more times
*? Repeats a character zero or more times (non-greedy)
+ Repeats a character one or more times
+? Repeats a character one or more times (non-greedy)
[aeiou] Matches a single character in the listed set
[^XYZ] Matches a single character not in the listed set
[a-z0-9] The set of characters can include a range
( Indicates where string extraction is to start
) Indicates where string extraction is to end##Objects
##Web Services, API
##Web Scraping, BeautifullSoup