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

import sys
sys.modules.keys()

An approximation of getting all imports for the current module only would be to inspect globals() for modules:

import types
def imports():
    for name, val in globals().items():
        if isinstance(val, types.ModuleType):
            yield val.__name__

This won't return local imports, or non-module imports like from x import y. Note that this returns val.__name__ so you get the original module name if you used import module as alias; yield name instead if you want the alias.

Find the intersection of sys.modules with globals:

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

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.

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

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.

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.

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.

There are a lot of contorted answers here, some of which doesn't work as expected on latest Python 3.10. The best solution for getting the script's fully imported modules, but not the internal __builtins__ or sub-imports, is by using this:

# import os, sys, time, rlcompleter, readline
from types import ModuleType as MT
all = [k for k,v in globals().items() if type(v) is MT and not k.startswith('__')]
", ".join(all)

# 'os, sys, time, rlcompleter, readline'

The result above was inspired by the answer above by @marcin, which is basically taking the union of all the modules and the globals:

# import os, sys, time, rlcompleter, readline
modulenames = set(sys.modules) & set(globals())
allmodules = [sys.modules[name] for name in modulenames]
for i in allmodules: print (' {}\n'.format(i))

#<module 'time' (built-in)>
#<module 'os' from 'C:\\Python310\\lib\\os.py'>
#<module 'sys' (built-in)>
#<module 'readline' from 'C:\\Python310\\lib\\site-packages\\readline.py'>
#<module 'rlcompleter' from 'C:\\Python310\\lib\\rlcompleter.py'>

Also notice how the order of the imports is also reflected in the 1st solution, but not in the last. However the module path is also given in the 2nd solution which could be useful in debugging.

_{PS. Not sure I'm using the correct vocabulary here, so please make a comment if I need to be corrected.}

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!

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)