Python: List Modules, Search Path, Loaded Modules
List Available Modules
To list all modules, type pydoc modules in terminal.
or in Python
print (help('modules') )
# -*- coding: utf-8 -*- # prints a list of existing modules print(help('modules'))
Please wait a moment while I gather a list of all available modules... CDROM binhex itertools site DLFCN bisect json sitecustomize IN builtins keyword smtpd TYPES bz2 lib2to3 smtplib ...
Note: in Ubuntu Linux, as of , there's a bug that both pydoc modules and help('modules') will crash Python. Use python3 instead.
sudo apt-get install python3
pydoc3 modules
Reading Module Documentation
To read the doc of a module, in terminal, type pydoc module_name, or in Python program call help(module_name).
# -*- coding: utf-8 -*- # python import os # print the module's online manual print help(os)
Note: the documentation from pydoc is not identical to the official documentation. Doc from pydoc is generated from the module source code, and is terse and technical.
List Module's Function/Variable Names
dir(module_name)→ list all names exported by the module module_name.dir()→ list all names in current scope (but not standard functions). To list standard functions,import __builtin__first, thendir(__builtin__).
# -*- coding: utf-8 -*- # python import re # print all names exported by the module print dir(re) # sample output: # ['DEBUG', 'DOTALL', 'I', 'IGNORECASE', 'L', 'LOCALE', 'M', 'MULTILINE', 'S', 'Scanner', 'T', 'TEMPLATE', 'U', 'UNICODE', 'VERBOSE', 'X', '_MAXCACHE', '__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '__version__', '_alphanum', '_cache', '_cache_repl', '_compile', '_compile_repl', '_expand', '_locale', '_pattern_type', '_pickle', '_subx', 'compile', 'copy_reg', 'error', 'escape', 'findall', 'finditer', 'match', 'purge', 'search', 'split', 'sre_compile', 'sre_parse', 'sub', 'subn', 'sys', 'template']
Using Module
import module_name → load a module.
module_name.function_name → call a function in module.
# -*- coding: utf-8 -*- # python # import the standard module named os import os # example of using a function print 'current dir is:', os.getcwd()
Import Function Names from Module
Module's function name can be imported directly by the syntax:
from module_name import name_1, name_2, …→ import several functions.from module_name import *→ import all functions.
# -*- coding: utf-8 -*- # python from os import getcwd print getcwd() # current working dir
Default “module”
All global (variable/function) names in Python are considered to be in the pseudo-module namespace named __main__.
# -*- coding: utf-8 -*- # python print dir() # ['__builtins__', '__doc__', '__file__', '__name__', '__package__'] print dir("__main__") # ['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']
Module Search Paths
Python module search paths is stored in the variable sys.path.
# -*- coding: utf-8 -*- # python import sys import pprint # pretty print module search paths pprint.pprint(sys.path) # sample output """ ['/home/joe/web/', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-linux2', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PIL', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client', '/usr/lib/python2.7/dist-packages/ubuntuone-client', '/usr/lib/python2.7/dist-packages/ubuntuone-control-panel', '/usr/lib/python2.7/dist-packages/ubuntuone-couch', '/usr/lib/python2.7/dist-packages/ubuntuone-installer', '/usr/lib/python2.7/dist-packages/ubuntuone-storage-protocol'] """
List Loaded Modules
Loaded module names is stored in the variable sys.modules.
# -*- coding: utf-8 -*- # python import sys import pprint # pretty print loaded modules pprint.pprint(sys.modules) # sample output """ {'UserDict': <module 'UserDict' from '/usr/lib/python2.7/UserDict.pyc'>, '__builtin__': <module '__builtin__' (built-in)>, '__main__': <module '__main__' from '/home/joe/web/test.py'>, '_abcoll': <module '_abcoll' from '/usr/lib/python2.7/_abcoll.pyc'>, '_codecs': <module '_codecs' (built-in)>, '_sre': <module '_sre' (built-in)>, '_warnings': <module '_warnings' (built-in)>, '_weakref': <module '_weakref' (built-in)>, '_weakrefset': <module '_weakrefset' from '/usr/lib/python2.7/_weakrefset.pyc'>, 'abc': <module 'abc' from '/usr/lib/python2.7/abc.pyc'>, 'apport_python_hook': <module 'apport_python_hook' from '/usr/lib/python2.7/dist-packages/apport_python_hook.pyc'>, 'cStringIO': <module 'cStringIO' (built-in)>, 'codecs': <module 'codecs' from '/usr/lib/python2.7/codecs.pyc'>, 'copy_reg': <module 'copy_reg' from '/usr/lib/python2.7/copy_reg.pyc'>, 'encodings': <module 'encodings' from '/usr/lib/python2.7/encodings/__init__.pyc'>, 'encodings.__builtin__': None, 'encodings.aliases': <module 'encodings.aliases' from '/usr/lib/python2.7/encodings/aliases.pyc'>, 'encodings.codecs': None, 'encodings.encodings': None, 'encodings.utf_8': <module 'encodings.utf_8' from '/usr/lib/python2.7/encodings/utf_8.pyc'>, 'errno': <module 'errno' (built-in)>, 'exceptions': <module 'exceptions' (built-in)>, 'genericpath': <module 'genericpath' from '/usr/lib/python2.7/genericpath.pyc'>, 'linecache': <module 'linecache' from '/usr/lib/python2.7/linecache.pyc'>, 'os': <module 'os' from '/usr/lib/python2.7/os.pyc'>, 'os.path': <module 'posixpath' from '/usr/lib/python2.7/posixpath.pyc'>, 'posix': <module 'posix' (built-in)>, 'posixpath': <module 'posixpath' from '/usr/lib/python2.7/posixpath.pyc'>, 'pprint': <module 'pprint' from '/usr/lib/python2.7/pprint.pyc'>, 're': <module 're' from '/usr/lib/python2.7/re.pyc'>, 'signal': <module 'signal' (built-in)>, 'site': <module 'site' from '/usr/lib/python2.7/site.pyc'>, 'sitecustomize': <module 'sitecustomize' from '/usr/lib/python2.7/sitecustomize.pyc'>, 'sre_compile': <module 'sre_compile' from '/usr/lib/python2.7/sre_compile.pyc'>, 'sre_constants': <module 'sre_constants' from '/usr/lib/python2.7/sre_constants.pyc'>, 'sre_parse': <module 'sre_parse' from '/usr/lib/python2.7/sre_parse.pyc'>, 'stat': <module 'stat' from '/usr/lib/python2.7/stat.pyc'>, 'sys': <module 'sys' (built-in)>, 'sysconfig': <module 'sysconfig' from '/usr/lib/python2.7/sysconfig.pyc'>, 'traceback': <module 'traceback' from '/usr/lib/python2.7/traceback.pyc'>, 'types': <module 'types' from '/usr/lib/python2.7/types.pyc'>, 'warnings': <module 'warnings' from '/usr/lib/python2.7/warnings.pyc'>, 'zipimport': <module 'zipimport' (built-in)>} """
Python: Paths Topic
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