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pythonpython-module
Dave Forgac
Dave Forgac

Reputation: 3336

How can I access the list of modules that Python's help('modules') displays?

How can I access the list of modules that Python's help('modules') displays? It shows the following:

>>> help('modules')

Please wait a moment while I gather a list of all available modules...

...[list of modules]...
MySQLdb             codeop              mailman_sf          spwd
OpenSSL             collections         markupbase          sqlite3
Queue               colorsys            marshal             sre
...[list of modules]...

Enter any module name to get more help.  Or, type "modules spam" to search
for modules whose descriptions contain the word "spam".

>>>

I can view the list in the output but would like to access this as a list from within a Python program. How can I do this?

Upvotes: 5

Views: 1654

Answers (4)

Joao Figueiredo
Joao Figueiredo

Reputation: 3188

Those will only list modules not included in the standard library, but may be useful,

subprocess.call( pip freeze)

subprocess.call( yolk -l)

Upvotes: 1

ekhumoro
ekhumoro

Reputation: 120698

The list of modules comes ultimately from a combination of sys.builtin_module_names and the output of pkgutil.walk_packages:

import sys
from pkgutil import walk_packages

modules = set()

def callback(name, modules=modules):
    if name.endswith('.__init__'):
        name = name[:-9] + ' (package)'
    if name.find('.') < 0:
        modules.add(name)

for name in sys.builtin_module_names:
    if name != '__main__':
        callback(name)

for item in walk_packages(onerror=callback):
    callback(item[1])

for name in sorted(modules, key=lambda n: n.lower()):
    print name

It should be noted that creating the list has the consequnce that all the modules will be imported (you can easily verify this for yourself by checking the length of sys.modules before and after calling help('modules')).

Another thing to note is that the output of walk_packages depends on the current state of sys.path - so the results may not always match the output of help.

Upvotes: 1

Roman Bodnarchuk
Roman Bodnarchuk

Reputation: 29737

You can mimic all the help does by yourself. Built-in help uses pydoc, that uses ModuleScanner class to get information about all available libs - see line 1873 in pydoc.py.

Here is a bit modified version of code from the link:

>>> modules = []
>>> def callback(path, modname, desc, modules=modules):
    if modname and modname[-9:] == '.__init__':
        modname = modname[:-9] + ' (package)'
    if modname.find('.') < 0:
        modules.append(modname)

>>> def onerror(modname):
    callback(None, modname, None)

>>> from pydoc import ModuleScanner 
>>> ModuleScanner().run(callback, onerror=onerror)
>>> len(modules)
379
>>> modules[:10]
['__builtin__', '_ast', '_bisect', '_codecs', '_codecs_cn', '_codecs_hk', '_codecs_iso2022', '_codecs_jp', '_codecs_kr', '_codecs_tw']
>>> len(modules)
379

Upvotes: 4

Don Question
Don Question

Reputation: 11624

There are more then one way. You could try:

import sys

mod_dict = sys.modules

for k,v in mod_dict.iteritems():
    print k,v

Upvotes: 2

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