How to set path for installed modules on computer with 2 versions of python

Question

I haven't tried yet out of fear I'll mess up more than I'll fix but I don't know if I can use PYTHONPATH to fix my problem. I've installed python 2.7.10 and python 3.4.2 on my Macbookpro. Python2.7 doesn't have problems, only 3.4 does. I'm afraid if I use PYTHONPATH to fix python3, it will affect python2.

Anyway, I've run:

sudo pip install blah2
sudo pip3 install blah3
pip freeze | grep blah2
blah2=2.12345
pip3 freeze | grep blah3
blah3=3.12345

and I can see I've installed the respective modules for python2 and python3 as pip freeze has shown. However, I keep getting errors when running scripts from cmd line for python 3.4 that say the module isn't found.

On further investigation using sys.path in my script, I can see python3 from cmd line is looking for modules at

/usr/local/lib/python3.4/site-packages

which doesn't have anything inside of it, whereas Idle for python 3.4 is looking at

/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages

which has tons of files in there.

I don't know why this got messed up in the first place or what I forgot to do to mess it up like this but how do I tell python 3.4 to look at the /Library location for modules?

The funny thing is both python2 and 3 were installed from tar/gzip files. I ran both using the

configure; make ;make install

command but for some reason python2 is fine but python3 isn't.

Have you tried out conda or pyenv instead? There are a handful of tools out there that manage this for you instead of you having to figure out all the weird tricks needed to make it work. — bheklilr
– bheklilr, Commented Dec 4, 2015 at 3:55
No, I didn't even know they existed. Thanks for the suggestion. — Classified
– Classified, Commented Dec 4, 2015 at 4:11

Kamyar Infinity · Accepted Answer · 2015-12-04 04:14:40Z

2

This may mean the pip3 is installing to that different path. Take a look at pip3 script and see where it is putting the package files. In my case the first line of it looks like this:

#!/opt/local/Library/Frameworks/Python.framework/Versions/3.4/bin/python3.4

Look if this is the path to the correct python3 binary. If it's not, you have two options: change this first line of pip3 to the path of your desired python3 binary, or just forget about it, use the pip directly with python3 command:

python3 -m pip install blah3

This should use the appropriate path when installing the package.

answered Dec 4, 2015 at 4:14

Kamyar Infinity

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