How do I tell python3 to look for the right modules?

Question

my first question here on stackoverflow. i did some research before, and people often got the same problem as i do. but their solutions didn't work out for me so far.

i've installed python3 with homebrew on my mac. the path is set in the ~/.bash_profile to

export PATH=/usr/local/bin:$PATH.

that works quite well, even with opencv3. last week i've wanted to import matplotlib... and that doesn't work.

python3 looks for its modules in python2.7 somehow. any recommendations?

MacBook-Pro:Desktop -----$ python3 webcam_test.py
Traceback (most recent call last):
  File "webcam_test.py", line 3, in <module>
    import matplotlib.pyplot as plt
  File "/usr/local/lib/python2.7/site-packages/matplotlib/pyplot.py", line 29, in <module>
    import matplotlib.colorbar
  File "/usr/local/lib/python2.7/site-packages/matplotlib/colorbar.py", line 32, in <module>
    import matplotlib.artist as martist
  File "/usr/local/lib/python2.7/site-packages/matplotlib/artist.py", line 15, in <module>
    from .transforms import (Bbox, IdentityTransform, TransformedBbox,
  File "/usr/local/lib/python2.7/site-packages/matplotlib/transforms.py", line 39, in <module>
    from matplotlib._path import (affine_transform, count_bboxes_overlapping_bbox,
ImportError: dlopen(/usr/local/lib/python2.7/site-packages/matplotlib/_path.so, 2): Symbol not found: _PyCObject_Type
  Referenced from: /usr/local/lib/python2.7/site-packages/matplotlib/_path.so
  Expected in: flat namespace
 in /usr/local/lib/python2.7/site-packages/matplotlib/_path.so

import sys; print(sys.path) gives me:

>>> import sys; print(sys.path)
['', '/usr/local/lib/python3', '/Users/----/Desktop', '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/lib/python36.zip', '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/lib-dynload', '/usr/local/lib/python3.6/site-packages', '/usr/local/Cellar/matplotlib/2.0.2/libexec/lib/python3.6/site-packages', '/usr/local/Cellar/numpy/1.13.3/libexec/nose/lib/python3.6/site-packages', '/usr/local/lib/python2.7/site-packages', '/usr/local/Cellar/matplotlib/2.0.2/libexec/lib/python2.7/site-packages', '/usr/local/Cellar/numpy/1.13.3/libexec/nose/lib/python2.7/site-packages', '/usr/local/opt/opencv/lib/python2.7/site-packages', '/usr/local/opt/opencv/lib/python3.6/site-packages']
>>>

seems a bit long to me...

edit 2:

just checked my /usr/local/bin/ . it's a bit messy i guess. amongst other files there are aliases of python2, python2.7, python3, python3.6, python3.6m and pythonX.X-config for each version. but no python itself. can i remove some of those? and shouldn't there be python files itself?

edit3:

so today i deleted everything and started from scratch. python3 with brew numpy and even opencv3 worked fine. import cv2 made no problems at all. then i tried to import matplotlib which threw

 mport matplotlib
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: bad magic number in 'matplotlib': b'\x03\xf3\r\n'

so i checked my sys.path

>>> sys.path
['', '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/lib/python36.zip', '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/lib-dynload', '/usr/local/lib/python3.6/site-packages', '/usr/local/opt/opencv/lib/python2.7/site-packages', '/usr/local/opt/opencv/lib/python3.6/site-packages']

2.7 shoulnd't be in there, right? how can i remove this one? any other recommendations?

I dont have a macbook, but on windows I look for `PATH` and `PYTHONPATH` environmental variables and repoints them to python-3 since I have both 2.7 and 3.x on same laptop. — Anil_M, Oct 02 '17 at 20:00
you can click the [edit](https://stackoverflow.com/posts/46532833/edit) button under the question and add more info to your post. — chickity china chinese chicken, Oct 02 '17 at 20:09
Ok. You definitely have Python 2.7 stuff mixed in with the Python 3.6 stuff. That shouldn't happen under normal circumstances... — PM 2Ring, Oct 02 '17 at 20:16

score 0 · Answer 1 · answered Oct 02 '17 at 20:07

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It appears that the Python 2 in conflicting with Python 3 in your path. To fix it try this answer: "This package should not be accessible on Python 3" when running python3

All credit to Charles Duffy.

Hope this helps!

answered Oct 02 '17 at 20:07

Ben10

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score 0 · Answer 2 · edited Oct 02 '17 at 20:28

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Add the following line in your bash_profile file followed by log out and login:

set PYTHONPATH=/your python deployment directory/

edited Oct 02 '17 at 20:28

Martin Evans

45,791
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answered Oct 02 '17 at 20:12

Abhijit Pritam Dutta

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sadly that didn't changed anything – Mr.Sh4nnon Oct 02 '17 at 20:21
Can you check your 'path' variable. If it still refers to python 2.7 just change it to the latest version and try again. – Abhijit Pritam Dutta Oct 02 '17 at 20:29
how do i check that? which pyhton3 tells me /usr/local/bin/python3 – Mr.Sh4nnon Oct 02 '17 at 20:33
echo $path gives me a complete blank response. – Mr.Sh4nnon Oct 02 '17 at 20:40
It might be in capital PATH. If echo $PATH also giving you blank you can try with export PATH=\yourNewPythonHomedirectory\:$PATH in your bash_profile file and try – Abhijit Pritam Dutta Oct 02 '17 at 20:50
sorry my fault. that shows me /usr/local/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/Library/TeX/texbin – Mr.Sh4nnon Oct 02 '17 at 20:58
have you seen my last edit? in my opinion usr/local/bin is somehow messed up. – Mr.Sh4nnon Oct 02 '17 at 20:59
just execute python --version and check whether python executable is correct or not – Abhijit Pritam Dutta Oct 02 '17 at 21:10
python --version shows 2.7.10 if i type python3 --version i get 3.6.2 – Mr.Sh4nnon Oct 02 '17 at 21:22
did you add export PATH=\yourNewPythonHomedirectory\:$PATH in you bash_profile file? you need to logout and log in again and check with echo $PATH to check whether new python location is set at the beginning of the path variable or not – Abhijit Pritam Dutta Oct 02 '17 at 21:41

How do I tell python3 to look for the right modules?

2 Answers2