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
– Nico Schlömer, Commented Jun 15, 2018 at 9:20
@JodhSingh This is about whether a package is installed with pip. Perhaps you have a suggestion on how to improve the wording? — Nico Schlömer
– Nico Schlömer, Commented Jun 15, 2018 at 9:33
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
– luator, Commented Feb 13, 2020 at 8:25
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
– sinoroc, Commented Feb 13, 2020 at 9:47

sinoroc · Accepted Answer · 2020-02-14 13:49:21Z

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, 2020 at 13:49

answered Feb 13, 2020 at 15:10

sinoroc

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2 Comments

Nico Schlömer Over a year ago

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.

sinoroc Over a year ago

Yes, this should be rewritten with the proper checks and/or try clauses in place.

Nils Werner · Accepted Answer · 2018-06-15 10:27:51Z

0

You said subprocess.call() is allowed, so

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

edited Jun 15, 2018 at 10:27

answered Jun 15, 2018 at 9:22

Nils Werner

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2 Comments

Nico Schlömer Over a year ago

Gives False for me although requests is installed with pip.

Nils Werner Over a year ago

I forgot a not()... retval = 0 means success, but casts to False. retval != 0 means failed but casts to True :-)

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