Python – Revert the `–no-site-packages` option with virtualenv

There are two types of site-packages directories, global and per user.

1. Global site-packages ("dist-packages") directories are listed in sys.path when you run:

   python -m site
   

   For a more concise list run getsitepackages from the site module in Python code:

   python -c 'import site; print(site.getsitepackages())'
   

   Note: With virtualenvs getsitepackages is not available, sys.path from above will list the virtualenv's site-packages directory correctly, though. In Python 3, you may use the sysconfig module instead:

   python3 -c 'import sysconfig; print(sysconfig.get_paths()["purelib"])'
   

2. The per user site-packages directory (PEP 370) is where Python installs your local packages:

   python -m site --user-site
   

   If this points to a non-existing directory check the exit status of Python and see python -m site --help for explanations.

   Hint: Running pip list --user or pip freeze --user gives you a list of all installed per user site-packages.

Practical Tips

• <package>.__path__ lets you identify the location(s) of a specific package: (details)

  $ python -c "import setuptools as _; print(_.__path__)"
  ['/usr/lib/python2.7/dist-packages/setuptools']
  

• <module>.__file__ lets you identify the location of a specific module: (difference)

  $ python3 -c "import os as _; print(_.__file__)"
  /usr/lib/python3.6/os.py
  

• Run pip show <package> to show Debian-style package information:

  $ pip show pytest
  Name: pytest
  Version: 3.8.2
  Summary: pytest: simple powerful testing with Python
  Home-page: https://docs.pytest.org/en/latest/
  Author: Holger Krekel, Bruno Oliveira, Ronny Pfannschmidt, Floris Bruynooghe, Brianna Laugher, Florian Bruhin and others
  Author-email: None
  License: MIT license
  Location: /home/peter/.local/lib/python3.4/site-packages
  Requires: more-itertools, atomicwrites, setuptools, attrs, pathlib2, six, py, pluggy
  

figure tells you the call signature:

from matplotlib.pyplot import figure

figure(figsize=(8, 6), dpi=80)

figure(figsize=(1,1)) would create an inch-by-inch image, which would be 80-by-80 pixels unless you also give a different dpi argument.