Check if Python Package is installed

Question

What\'s a good way to check if a package is installed while within a Python script? I know it\'s easy from the interpreter, but I need to do it within a script.

I g

Answer 1

I'd like to add some thoughts/findings of mine to this topic. I'm writing a script that checks all requirements for a custom made program. There are many checks with python modules too.

There's a little issue with the

try:
   import ..
except:
   ..

solution. In my case one of the python modules called python-nmap, but you import it with import nmap and as you see the names mismatch. Therefore the test with the above solution returns a False result, and it also imports the module on hit, but maybe no need to use a lot of memory for a simple test/check.

I also found that

import pip
installed_packages = pip.get_installed_distributions()

installed_packages will have only the packages has been installed with pip. On my system pip freeze returns over 40 python modules, while installed_packages has only 1, the one I installed manually (python-nmap).

Another solution below that I know it may not relevant to the question, but I think it's a good practice to keep the test function separate from the one that performs the install it might be useful for some.

The solution that worked for me. It based on this answer How to check if a python module exists without importing it

from imp import find_module

def checkPythonmod(mod):
    try:
        op = find_module(mod)
        return True
    except ImportError:
        return False

NOTE: this solution can't find the module by the name python-nmap too, I have to use nmap instead (easy to live with) but in this case the module won't be loaded to the memory whatsoever.