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I have Python version 3.5.2 and I have pip3, so I did

sudo pip3 install pyqt5

That got installed in /usr/local/lib/python3.5/dist-packages

However when I enter my python 3 interpreter and type

import PyQt5

it gives me an error that it can't find the module named PyQt5.

So I tried adding the /usr/local/lib/python3.5/dist-packages path to PYTHONPATH by doing

export PYTHONPATH=$PYTHONPATH:/usr/local/lib/python3.5/dist-packages

but that didn't fix anything. How do I make Python 3.5.2 detect PyQt5?

Shadowfax
  • 201

1 Answers1

5

Thanks to George I slowly got to the answer. The root of the problem lies in that I installed my Python 3.5.2 version from a source rather than from the Ubuntu aptitude package manager.

Basically, if Python is installed from a source, then, to look for 3rd party packages, it uses /usr/local/lib/python3.5/site-packages, but if it was installed using apt, then Python looks in /usr/local/lib/python3.5/dist-packages. This is to make sure that the several Python versions don't get tangled up. Here is another question that explains: what is the difference between dist-packages and site-packages?.

Solution:

My Python3 installation was looking into site-packages and ignoring dist-packages, so I added a path file to make it look inside dist-packages as well.

cd /usr/local/lib/python3.5/site-packages
sudo vim dist-packages.pth
(Press i to go into insert mode inside Vim)
../dist-packages
:x (and Press Enter/Return)

Now when Python looks inside /site-packages, it finds dist-packages.pth which makes it go into /dist-packages.

Other Solution:

Someone else had a problem exactly the reverse of mine, where their Python installation only looked inside /dist-packages, so they used the exact same method as above except instead of making a dist-packages.pth file (containing ../dist-packages) inside /site-packages, they made a site-packages.pth file (containing ../site-packages inside /dist-packages.

Check if it worked:

The easy way to check if this worked is to go into your Python interpreter and print sys.path. It should now contain both package paths:

charliebrown@playground:/usr/local/lib/python3.5/site-packages$ python3
Python 3.5.2 (default, Nov 19 2016, 02:36:25) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys; print(sys.path)
['', '/usr/local/lib/python35.zip', '/usr/local/lib/python3.5',     '/usr/local/lib/python3.5/plat-linux', '/usr/local/lib/python3.5/lib-dynload', 
'/usr/local/lib/python3.5/site-packages', '/usr/local/lib/python3.5/dist-packages']

I hope this helps someone one day...

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Shadowfax
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