Checking if a package is installed specifically via pip

Question

Checking if a particular package is available from within Python can be done via

try:
    import requests
except ImportError:
    available = False
else: 
    available = True

Additionally, I would like to know if the respective package has been installed with pip (and can hence been updated with pip install -U package_name).

Any hints?

It needs to be in code. If necessary, parsing the output of `subprocess` could be it. — Nico Schlömer, Jun 15 '18 at 09:20
@JodhSingh This is about whether a package is installed _with pip_. Perhaps you have a suggestion on how to improve the wording? — Nico Schlömer, Jun 15 '18 at 09:33
I don't think this is a duplicate of the linked question. The linked one is about finding out if a package is installed. This one is specifically about finding out if it is installed *with pip*. — luator, Feb 13 '20 at 08:25
Agreed, not a duplicate. I believe it can be solved with something like that: `import pkg_resources; pkg_resources.get_distribution('requests').get_metadata('INSTALLER')`. — sinoroc, Feb 13 '20 at 09:47

sinoroc · Accepted Answer · 2020-02-14T13:49:21.667

2

I believe one way to figure out if a project has been installed by pip is by looking at the content of the INSTALLER text file in the distribution's dist-info directory for this project. With pkg_resources from setuptools this can be done programmatically like the following (error checking omitted):

import pkg_resources

pkg_resources.get_distribution('requests').get_metadata('INSTALLER')

This would return pip\n, in case requests was indeed installed by pip.

edited Feb 14 '20 at 13:49

answered Feb 13 '20 at 15:10

sinoroc

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Well, this works if it is indeed installed via pip. It fails with `FileNotFound` for Debian-installed packages because, e.g., `/usr/lib/python3/dist-packages/requests-2.22.0.egg-info/INSTALLER` is not installed there. That's good enough for me. – Nico Schlömer Feb 14 '20 at 13:38
Yes, this should be rewritten with the proper checks and/or try clauses in place. – sinoroc Feb 14 '20 at 13:43

Nils Werner · Answer 2 · 2018-06-15T10:27:51.223

0

You said subprocess.call() is allowed, so

available = not(subprocess.call(["pip", "show", "requests"]))

edited Jun 15 '18 at 10:27

answered Jun 15 '18 at 09:22

Nils Werner

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Gives `False` for me although `requests` is installed with pip. – Nico Schlömer Jun 15 '18 at 09:33
I forgot a `not()`... `retval = 0` means `success`, but casts to `False`. `retval != 0` means `failed` but casts to `True` :-) – Nils Werner Jun 15 '18 at 10:28

Checking if a package is installed specifically via pip

2 Answers2