import batteries
The modules you never knew you needed
Ivana Kellyerova | June 8, 2018
Batteries Included
The Python standard library can do anything.
abstrusegoose.com/81 (license)
Okay, maybe not anything.
The Noteworthy
(for all sorts of reasons)
keyword
Determine if a string is a Python keyword.
>>> import keyword
>>> keyword.iskeyword('djangopony')
False
>>> keyword.iskeyword('while')
True
>>> keyword.kwlist
['False', 'None', 'True', 'and', 'as', 'assert', 'break', 'class',
'continue', 'def', 'del', 'elif', 'else', 'except', 'finally',
'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda',
'nonlocal', 'not', 'or', 'pass', 'raise', 'return', 'try',
'while', 'with', 'yield']
... that's it.
tabnanny
Check files for ambiguous indentation.
>>> import tabnanny
>>> tabnanny.check('input/perfect_python_file.py')
>>> # ^ Internally raises tabnanny.NannyNag
turtle
Simple visual programming language.
docs.python.org/3/library/turtle.html
$ python3 -m turtle
webbrowser
Your partner for all your browser-opening needs.
>>> import webbrowser
>>> webbrowser.open('https://www.amarion.net')
True
sndhdr
Determine what kind of data there is in a sound file.
>>> import sndhdr
>>> # We like descriptive function names
>>> sndhdr.what('path/to/music/file.mp3')
calendar
General calendar-related functions
colorsys
RGB, HSV, HLS, YIQ color conversion
cmd
Build your custom interactive shell
aifc
Read and write AIFF and AIFC files
doctest
Test code examples in docstrings
html
HTML manipulation
sunau
Support for the Sun AU sound format
telnet
Telnet client
zipfile
Read and write ZIP files
binhex4
Encode and decode binhex4
dis
Disassemble Python bytecode
grp
Support for Unix groups
mailbox
Manipulate mailboxes in various formats
Also Noteworthy
(this time for different reasons)
2to3
Automatic Python 2 to 3 code translation.
def greet(name):
print "Hello, {0}!".format(name)
print "What's your name?"
name = raw_input()
greet(name)
$ 2to3 example.py
def greet(name):
print("Hello, {0}!".format(name))
print("What's your name?")
name = input()
greet(name)
builtins
Access builtin objects.
>>> open
<built-in function open>
>>> def open(args):
... do_something()
>>> open
<function open at 0x7f1216cfa950>
>>> # Hmm, can't use the builtin open anymore
>>> import builtins
>>> with builtins.open('filename', 'r'):
... do_something_else()
textwrap
Paragraph wrapping & indentation management.
>>> import textwrap
>>> long_string = """\
... This is a long paragraph spanning multiple lines.
... A very good candidate for a triple-quoted string.
... """
>>> long_string
" This is a long paragraph spanning multiple lines.\n A very good
candidate for a triple-quoted string.\n"
textwrap
>>> # Get rid of leading whitespace
>>> long_string = textwrap.dedent(long_string)
>>> long_string
"This is a long paragraph spanning multiple lines.\nA very good
candidate for a triple-quoted string.\n"
>>> # Wrap to a specific number of characters
>>> textwrap.fill(long_string, width=40)
"This is a long paragraph spanning\nmultiple lines. A very good
candidate\nfor a triple-quoted string.\n"
>>> # Cut at the last possible word boundary to fill width
>>> textwrap.shorten(long_string, width=10, placeholder='...')
'This is...'
timeit
$ python3 -m timeit '"-".join(str(n) for n in range(100))'
10000 loops, best of 3: 30.2 usec per loop
$ python3 -m timeit '"-".join([str(n) for n in range(100)])'
10000 loops, best of 3: 27.5 usec per loop
$ python3 -m timeit '"-".join(map(str, range(100)))'
10000 loops, best of 3: 23.2 usec per loop
>>> import timeit
>>> timeit.timeit('"-".join(str(n) for n in range(100))',
>>> number=10000)
0.3018611848820001
>>> timeit.timeit('"-".join([str(n) for n in range(100)])',
>>> number=10000)
0.2727368790656328
>>> timeit.timeit('"-".join(map(str, range(100)))', number=10000)
0.23702679807320237
pprint
String representation for humans.
>>> games = {'aaa': {'fps': ['Counter Strike', 'Unreal Tournament'],
... 'rpg': ['Dragon Age', 'Mass Effect', 'Neverwinter Nights']},
... 'oldies': {'pointnclick': ['Legend of Kyrandia'],
... 'rpg': {'dungeon': ['Lands of Lore']}}, 'indie': {'stealth':
... ['Mark of the Ninja', 'Invisible Inc.'], 'roguelike': ['FTL',
... 'One More Dungeon'], 'puzzle': ['Braid'], 'action':
... ['Transistor', 'Bastion'], 'platformers': ['Hollow Knight', 'Eets
... Munchies'], 'dungeon': {'puzzle': ['Legend of Grimrock'],
... 'rhythm': ['Crypt of the Necrodancer']}}}
pprint
String representation for humans.
>>> from pprint import pprint
>>> pprint(games)
{'aaa': {'fps': ['Counter Strike', 'Unreal Tournament'],
'rpg': ['Dragon Age', 'Mass Effect', 'Neverwinter Nights']},
'indie': {'action': ['Transistor', 'Bastion'],
'dungeon': {'puzzle': ['Legend of Grimrock'],
'rhythm': ['Crypt of the Necrodancer']},
'platformer': ['Hollow Knight', 'Eets Munchies'],
'puzzle': ['Braid'],
'roguelike': ['FTL', 'One More Dungeon'],
'stealth': ['Mark of the Ninja', 'Invisible Inc.']},
'oldies': {'pointnclick': ['Legend of Kyrandia'],
'rpg': {'dungeon': ['Lands of Lore']}}}
itertools
Advanced iterators.
>>> import itertools
>>> seq1 = 'Today is Friday.'
>>> seq2 = [42, 47, 12, 9, 4, 0, 64]
>>> # Chain iterables
>>> for elem in itertools.chain(seq1, seq2):
... print(elem, end=' ')
T o d a y i s F r i d a y . 42 47 12 9 4 0 64
>>> list(itertools.dropwhile(lambda x: x > 30, seq2))
[12, 9, 4, 0, 64]
>>> [''.join(x) for x in itertools.permutations('abc', 2)]
['ab', 'ac', 'ba', 'bc', 'ca', 'cb']
functools
Higher order functions.
>>> import functools
>>> functools.reduce(
... lambda x, y: x + y,
... ['lab', 'rad', 'oo', 'dle']
... )
'labradoodle'
>>> print_word = functools.partial(print, end='')
>>> for i in range(4):
... print_word('cous')
couscouscouscous
traceback
Extract, format, print stack traces.
>>> def frobnicate():
... foobarify()
>>> def foobarify():
... bazificate()
>>> def bazificate():
... import traceback
... traceback.print_stack()
>>> frobnicate()
File "<stdin>", line 1, in <module>
File "<stdin>", line 2, in frobnicate
File "<stdin>", line 2, in foobarify
File "<stdin>", line 3, in bazificate
bisect
Efficient searching and maintenance of sorted lists.
>>> import bisect
>>> seq = [1, 4, 67, 89, 123, 200, 345, 678, 1274]
>>> # Use binary search to find out where an element is located:
>>> bisect.bisect_left(seq, 67)
2
>>> # Insert an element, keeping seq sorted:
>>> bisect.insort(seq, 470)
>>> seq
[1, 4, 67, 89, 123, 200, 345, 470, 678, 1274]
collections
Practical data structures.
>>> import collections
>>> counter = collections.Counter(['a', 'b', 'c', 'b', 'c', 'b'])
>>> counter
Counter({'b': 3, 'c': 2, 'a': 1}) # a dict with extra features
>>> counter['c']
2
>>> counter['notthere'] # 0 for any nonexistent value
0
collections
Practical data structures.
>>> releases = {'Braid': '2008', 'Hollow Knight': '2017'}
>>> releases['Pyre']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: 'Pyre'
>>> releases = collections.defaultdict(lambda: 'n/a')
>>> releases['Braid'] = '2008'
>>> releases['Hollow Knight'] = '2017'
>>> releases['Pyre']
'n/a'
The Python standard library can do almost anything.
bacon
>>> import bacon # ???
For the rest, there is the Python Package Index.
Twitter | @aerinthenniel
GitLab | jenx
GitHub | Eruraina
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