Installation

sudo pip install pythonpy
# restart your shell for tab completion to take effect

py 'expression' ≅ python -c 'print(expression)'

Float Arithmetic

$ py '3 * 1.5'
4.5

Import any module automatically

$ py 'math.exp(1)'
2.71828182846

$ py 'random.random()'
0.103173957713

$ py 'datetime.datetime.now?'
Help on built-in function now:

now(...)
      [tz] -> new datetime with tz's local day and time.

Lists are printed row by row

$ py 'range(3)'
0
1
2

$ py '[range(3)]'
[0, 1, 2]

py -x 'foo(x)' will apply foo to each line of input

Multiply each line of input by 7.

$ py 'range(3)' | py -x 'int(x)*7'
0
7
14

Append ".txt" to each line of input

$ py 'range(3)' | py -x 'x + ".txt"'
0.txt
1.txt
2.txt

Append ".txt" to every file in the directory

$ ls | py -x '"mv `%s` `%s.txt`" % (x,x)' | sh
# sharp quotes are swapped out for single quotes
# single quotes handle spaces in filenames

Get only even numbers

$ py 'range(8)' | py -x 'x if int(x)%2 == 0 else None'
0
2
4
6

py -fx 'predicate(x)' filters rows satisfying a condition

Get only odd numbers

$ py 'range(8)' | py -fx 'int(x)%2 == 1'
1
3
5
7

Get words starting with "and"

$ cat /usr/share/dict/words | py -fx 're.match(r"and", x)' | head -5
and
andante
andante's
andantes
andiron

Get verbs starting with ba

$ cat /usr/share/dict/words | py -fx 're.match(r"ba.*ing$", x)' | head -5
baaing
babbling
babying
babysitting
backbiting

Get long palindromes

$ cat /usr/share/dict/words | py -fx 'x==x[::-1] and len(x) >= 5' | head -5
civic
deified
kayak
level
ma'am

py -l will set l = list(sys.stdin)

Reverse the input

$ py 'range(3)' | py -l 'l[::-1]'
2
1
0

Sum the input

$ py 'range(3)' | py -l 'sum(int(x) for x in l)'
3

Count the lines of input

$ py 'range(17)' | py -l 'len(l)'
17

Count words beginning with each letter

$ cat /usr/share/dict/words | py -x 'x[0].lower()' | py -l 'collections.Counter(l).most_common(5)'
('s', 11327)
('c', 9521)
('p', 7659)
('b', 6068)
('m', 5922)

If you haven't had enough yet, check out the wiki