Asked  7 Months ago    Answers:  5   Viewed   33 times

I would like to get a list of Python modules, which are in my Python installation (UNIX server).

How can you get a list of Python modules installed in your computer?




Do not use with pip > 10.0!

My 50 cents for getting a pip freeze-like list from a Python script:

import pip
installed_packages = pip.get_installed_distributions()
installed_packages_list = sorted(["%s==%s" % (i.key, i.version)
     for i in installed_packages])

As a (too long) one liner:

sorted(["%s==%s" % (i.key, i.version) for i in pip.get_installed_distributions()])


['behave==1.2.4', 'enum34==1.0', 'flask==0.10.1', 'itsdangerous==0.24', 
 'jinja2==2.7.2', 'jsonschema==2.3.0', 'markupsafe==0.23', 'nose==1.3.3', 
 'parse-type==0.3.4', 'parse==1.6.4', 'prettytable==0.7.2', 'requests==2.3.0',
 'six==1.6.1', 'vioozer-metadata==0.1', 'vioozer-users-server==0.1', 


This solution applies to the system scope or to a virtual environment scope, and covers packages installed by setuptools, pip and (god forbid) easy_install.

My use case

I added the result of this call to my flask server, so when I call it with I get the list of packages installed on the server's virtualenv. It makes debugging a whole lot easier.


I have noticed a strange behaviour of this technique - when the Python interpreter is invoked in the same directory as a file, it does not list the package installed by

Steps to reproduce:

Create a virtual environment
$ cd /tmp
$ virtualenv test_env
New python executable in test_env/bin/python
Installing setuptools, pip...done.
$ source test_env/bin/activate
(test_env) $ 
Clone a git repo with
(test_env) $ git clone
Cloning into 'behave'...
remote: Reusing existing pack: 4350, done.
remote: Total 4350 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (4350/4350), 1.85 MiB | 418.00 KiB/s, done.
Resolving deltas: 100% (2388/2388), done.
Checking connectivity... done.

We have behave's in /tmp/behave:

(test_env) $ ls /tmp/behave/
Install the python package from the git repo
(test_env) $ cd /tmp/behave && pip install . 
running install
Installed /private/tmp/test_env/lib/python2.7/site-packages/enum34-1.0-py2.7.egg
Finished processing dependencies for behave==1.2.5a1

If we run the aforementioned solution from /tmp

>>> import pip
>>> sorted(["%s==%s" % (i.key, i.version) for i in pip.get_installed_distributions()])
['behave==1.2.5a1', 'enum34==1.0', 'parse-type==0.3.4', 'parse==1.6.4', 'six==1.6.1']
>>> import os
>>> os.getcwd()

If we run the aforementioned solution from /tmp/behave

>>> import pip
>>> sorted(["%s==%s" % (i.key, i.version) for i in pip.get_installed_distributions()])
['enum34==1.0', 'parse-type==0.3.4', 'parse==1.6.4', 'six==1.6.1']
>>> import os
>>> os.getcwd()

behave==1.2.5a1 is missing from the second example, because the working directory contains behave's file.

I could not find any reference to this issue in the documentation. Perhaps I shall open a bug for it.

Tuesday, June 1, 2021
answered 7 Months ago

Why not work out what's part of the standard library yourself?

import distutils.sysconfig as sysconfig
import os
std_lib = sysconfig.get_python_lib(standard_lib=True)
for top, dirs, files in os.walk(std_lib):
    for nm in files:
        if nm != '' and nm[-3:] == '.py':
            print os.path.join(top, nm)[len(std_lib)+1:-3].replace(os.sep, '.')


--- a bunch of other files ----

Edit: You'll probably want to add a check to avoid site-packages if you need to avoid non-standard library modules.

Thursday, July 15, 2021
answered 5 Months ago

You can use:


which will return a set of all free symbols.


>>> import sympy
>>> x, y, z = sympy.symbols('x:z')
>>> f = sympy.exp(x + y) - sympy.sqrt(z)
>>> f.free_symbols
set([x, z, y])
Tuesday, August 3, 2021
answered 4 Months ago

While being inside the virtualenv, please issue the following commands:

  • pip freeze
  • pip -V
  • python -V
  • which python
  • which pip

Share your results here to analyze it. I've also experienced pretty similar issues with the requests package before, but that happened on windows to me.

Saturday, August 7, 2021
answered 4 Months ago

This looks very much like a 32-bit/64-bit issue. If you are running 64-bit Python and you have 32-bit PythonWin you will see this sort of thing. Both win32gui and win32ui are .pyd files (DLLs) and they should live in Libsite-packageswin32 and Libsite-packagespythonwin respectively.

If you can see them there but the import is failing then it is likely they are the wrong bitness. A 64-bit executable cannot load a 32-bit DLL and vice versa, and if you try, in most cases the error message will tell you that the DLL you are trying to load isn't there. Even when you can see that it is.

Edit following exchange of comments with OP:

You will also get this sort of error with PythonWin if you put multiple imports in a single line. Follow PEP-8 and do one import to a line.

Friday, August 20, 2021
Óscar López
answered 4 Months ago
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