pip fails to install at same time of numpy

[Marco-Santoni]

If neither numpy nor pyearth are installed, and we install both of them by:

$ pip install -r requirements.txt

where requirements.txt:

numpy
scipy
-e git+https://github.com/jcrudy/py-earth.git#egg=py-earth

Throws ImportError: no module named numpy when installing pyearth. Refer to this issue and this issue to see how pip works in this case.

[jcrudy]

Thanks for reporting this @Marco-Santoni. From my quick read of pypa/pip#25 I think I understand the problem and how to fix it. I'll close this issue when fixed.

[Marco-Santoni]

Thanks, as I need to fix this asap, I've forked the repo and tried to fix the setup.py. However, as I'm not confident with setup.py and Cython, I cannot solve it. Could you please explain how you would solve it, or even commit the fix?

[jcrudy]

Well, I think the solution has to do with ilblackdragon's comment near the end of the pypa/pip#25.

It's better to handle egg_info, clean and help commands as special case (at least this is what has been done in scipy (https://github.com/scipy/scipy/blob/master/setup.py) and some other libraries that depend on numpy):

if '--help' in sys.argv[1:] or \
    sys.argv[1] in ('--help-commands', 'egg_info', 'clean', '--version'):
    ...
else:
    import numpy
    ...

The problem has to do with the fact that setup.py imports numpy in order to determine the build path. However, when just trying to get package dependency information on a system without numpy, this import causes an error. You would need to change setup.py so that it imports numpy only if it's actually going to do a build. At least that is my understanding.

I wish I could help more. If you have trouble, post more questions. I just have some projects going on right now and don't really have time to set up a testing environment and experiment with this. I should be able to respond to questions, though. If I get time, I will try to fix this from my end, but I expect that won't happen until next week.

[jcrudy]

Fixed by @mehdidc in PR #98.