[python] How to list imported modules?

How to enumerate all imported modules?

E.g. I would like to get ['os', 'sys'] from this code:

import os
import sys

I like using a list comprehension in this case:

>>> [w for w in dir() if w == 'datetime' or w == 'sqlite3']
['datetime', 'sqlite3']

# To count modules of interest...
>>> count = [w for w in dir() if w == 'datetime' or w == 'sqlite3']
>>> len(count)
2

# To count all installed modules...
>>> count = dir()
>>> len(count)

let say you've imported math and re:

>>import math,re

now to see the same use

>>print(dir())

If you run it before the import and after the import, one can see the difference.

This code lists modules imported by your module:

import sys
before = [str(m) for m in sys.modules]
import my_module
after = [str(m) for m in sys.modules]
print [m for m in after if not m in before]

It should be useful if you want to know what external modules to install on a new system to run your code, without the need to try again and again.

It won't list the sys module or modules imported from it.

Find the intersection of sys.modules with globals:

import sys
modulenames = set(sys.modules) & set(globals())
allmodules = [sys.modules[name] for name in modulenames]

Stealing from @Lila (couldn't make a comment because of no formatting), this shows the module's /path/, as well:

#!/usr/bin/env python
import sys
from modulefinder import ModuleFinder
finder = ModuleFinder()
# Pass the name of the python file of interest
finder.run_script(sys.argv[1])
# This is what's different from @Lila's script
finder.report()

which produces:

Name                      File
----                      ----

...
m token                     /opt/rh/rh-python35/root/usr/lib64/python3.5/token.py
m tokenize                  /opt/rh/rh-python35/root/usr/lib64/python3.5/tokenize.py
m traceback                 /opt/rh/rh-python35/root/usr/lib64/python3.5/traceback.py
...

.. suitable for grepping or what have you. Be warned, it's long!

If you want to do this from outside the script:

Python 2

from modulefinder import ModuleFinder
finder = ModuleFinder()
finder.run_script("myscript.py")
for name, mod in finder.modules.iteritems():
    print name

Python 3

from modulefinder import ModuleFinder
finder = ModuleFinder()
finder.run_script("myscript.py")
for name, mod in finder.modules.items():
    print(name)

This will print all modules loaded by myscript.py.

It's actually working quite good with:

import sys
mods = [m.__name__ for m in sys.modules.values() if m]

This will create a list with importable module names.

print [key for key in locals().keys()
       if isinstance(locals()[key], type(sys)) and not key.startswith('__')]