[Numpy-discussion] specifying numpy as dependency in your project, install_requires

josef.pktd at gmail.com josef.pktd at gmail.com
Fri Sep 21 21:28:22 EDT 2012

On Fri, Sep 21, 2012 at 5:39 PM, Nathaniel Smith <njs at pobox.com> wrote:
> On Fri, Sep 21, 2012 at 9:42 PM, Ralf Gommers <ralf.gommers at gmail.com> wrote:
>> Eh, just installing numpy with "python setup.py install" uses plain
>> distutils, not setuptools. So there indeed isn't an entry in
>> easy-install.pth.  Which some consider a feature:)
> I don't think this is correct. To be clear on the technical issue:
> what's going on is that when pip sees install_requires=["numpy"], it
> needs to check whether you already have the distribution called
> "numpy" installed. It turns out that in the wonderful world of python
> packaging, "distributions" are not quite the same as "packages", so it
> can't do this by searching PYTHONPATH for a "numpy" directory. What it
> does is search PYTHONPATH for a file named
> numpy-<version-number->.egg-info[1]. This isn't *quite* as dumb as it
> seems, because in practice there really isn't a 1-to-1 mapping between
> source distributions and installed packages, but it's... pretty dumb.
> Anyway. The problem is that Ralf installed numpy by doing an in-place
> build in his source tree, and then adding his source tree to his
> PYTHONPATH. But, he didn't put a .egg-info on his PYTHONPATH, so pip
> couldn't tell that numpy was installed, and did something dumb.
> So the question is, how do we get a .egg-info? For the specific case
> Ralf ran into, I'm pretty sure the solution is just that if you're
> clever enough to do an in-place build and add it to your PYTHONPATH,
> you should be clever enough to also run 'python setupegg.py egg_info'
> which will create a .egg-info to go with your in-place build and
> everything will be fine.
> The question is whether there are any other situations where this can
> break. I'm not aware of any. Contrary to what's claimed in the bit I
> quoted above, I just ran a plain vanilla 'python setup.py install' on
> numpy inside a virtualenv, and I ended up with a .egg-info installed.
> I'm pretty sure plain old distutils installs .egg-infos these days
> too. In that bug report Ralf says there's some problem with
> virtualenvs, but I'm not sure what (I use virtualenvs extensively and
> have never run into anything). Can anyone elaborate?
> [1] or several other variants, see some PEP or another for the tedious details.
> -n
> P.S.: yeah the thing where pip decides to upgrade the world is REALLY
> OBNOXIOUS. It also appears to be on the list to be fixed in the next
> release or the next release+1, so I guess there's hope?:
> https://github.com/pypa/pip/pull/571

In statsmodels we moved to the check that Ralf proposes, and no requires.

When I'm easy_installing a package I always need to watch out when a
package tries to upgrade numpy.
I just had to hit Crtl-C several times when the requires of pandas
tried to update my numpy version.


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