This is a cheat sheet for modules in Python. It provides examples for common module use and creation.
If you are doing a coding interview in Python, it is recommended to know all of these items, or to keep this list nearby.
It’s also a handy list at work, for when some syntax has slipped your mind. Module syntax changes drastically, and also in subtle ways, between languages, thus sometimes it’s nice to have a quick reference available.
Importing
# Import a specific symbol from a module from random import randint print( randint(5,10) ) # Import multiple symbols from a module from random import randint, choice # Import a module as a whole import math print( math.cos( math.pi ) ) # Import a module under a different name import itertools as it print( list( it.islice( it.cycle( 'ABCD' ), 10 ) ) ) # Import all symbols from a module from typing import * Vector = List[int]
Creating
A module is a directory with an __init__.py file.
# An __init__.py defines a directory as a module # It can be empty, but typically includes common useful classes from a module
These can be imported by the name of the directory. Directories within the directory where python is run are automatically added to the search path.
import sample_module from sample_module.common import *
Visibility
By default, all symbols without leading underscores are exported.
# common.py def _this_is_hidden(): print( "You can't see this" ) def this_is_public(): print( "This is a public function")
A list of explicit symbols can be provided with __all__.
__all__ = [ 'User', 'Account' ]
Relative Imports
Within a package you can import another module with a relative path.
from .types import User from . import common from .. import upper from ..upper import UpperClass
Executable Module
To make a module executable define a __main__.py file.
# __main__.py print( "This is the main function" )
Then run with python -m sample_module
