List all imported modules in a given python script:

$ modulereport setup.py
Full report:

  Name                      File
  ----                      ----
m __future__                /usr/lib/python3.4/__future__.py
m __main__                  setup.py
m _ast
m _bisect
m _bootlocale               /usr/lib/python3.4/_bootlocale.py
m _bz2                      /usr/lib/python3.4/lib-dynload/_bz2.cpython-34m-x86_64-linux-gnu.so
m _codecs
m _collections
m _collections_abc          /usr/lib/python3.4/_collections_abc.py
m _compat_pickle            /usr/lib/python3.4/_compat_pickle.py
m _ctypes                   /usr/lib/python3.4/lib-dynload/_ctypes.cpython-34m-x86_64-linux-gnu.so
m warnings                  /usr/lib/python3.4/warnings.py
m weakref                   /usr/lib/python3.4/weakref.py
m webbrowser                /usr/lib/python3.4/webbrowser.py
P xml                       /usr/lib/python3.4/xml/__init__.py
P xml.parsers               /usr/lib/python3.4/xml/parsers/__init__.py
m xml.parsers.expat         /usr/lib/python3.4/xml/parsers/expat.py
P xmlrpc                    /usr/lib/python3.4/xmlrpc/__init__.py
m xmlrpc.client             /usr/lib/python3.4/xmlrpc/client.py
m zipfile                   /usr/lib/python3.4/zipfile.py
m zipimport
m zlib

Missing modules:
? _dummy_threading imported from dummy_threading
? _frozen_importlib imported from importlib
? _sysconfigdata_dm imported from _sysconfigdata
? apport_python_hook imported from sitecustomize

Show help:

modulereport --help
usage: modulereport [-h] [-s, --skipreport] [-l, --loaded] [-m, --missing]

positional arguments:
  pathname          path to python file to analyze for imports

optional arguments:
  -h, --help        show this help message and exit
  -s, --skipreport  skip list of all modules
  -l, --loaded      show loaded modules
  -m, --missing     show missing modules
  -V,               show program's version number and exit


Modulereporter use modulefinder.ModuleFinder from Python 3 standard library. Source code for Lib/modulefinder.py.