[Numpy-discussion] "import numpy" is slow

David Cournapeau cournapeau@cslab.kecl.ntt.co...
Wed Jul 30 20:53:52 CDT 2008

On Thu, 2008-07-31 at 02:07 +0200, Andrew Dalke wrote:
> On Jul 30, 2008, at 10:59 PM, Stéfan van der Walt wrote:
> > I.e. most people don't start up NumPy all the time -- they import
> > NumPy, and then do some calculations, which typically take longer than
> > the import time.
> Is that interactively, or is that through programs?

Most people use it interactively, or for long running programs. Import
times only matters for interactive commands depending on numpy.

> and I am not saying to change this code.  Instead, I am asking for  
> limits on the eagerness, with a long-term goal of minimizing its use.

For new API, this is never done, and is a bug if it is. In scipy,
typically, import scipy does not import the whole subpackages list.

> I also haven't yet figured out how to get the regression tests to  
> run, and I'm not going to contribute patches without at least passing  
> that bare minimum.  BTW, how do I do that?  In the top-level there's  
> a 'test.sh' command but when I run it I get:

Argh, this file should have never ended here, that's entirely my fault.
It was a merge from a (at the time) experimental branch. I can't remove
it now because my company does not allow subversion access, but I will
fix this tonight. Sorry for the confusion.

> and when I run 'nosetests' in the top-level directory I get:
> ImportError: Error importing numpy: you should not try to import  
> numpy from
>          its source directory; please exit the numpy source tree, and  
> relaunch
>          your python intepreter from there.
> I couldn't find (in a cursory search) instructions for running self- 
> tests or regression tests.

You are supposed to run the tests on an installed numpy, not in the

import numpy
numpy.test(verbose = 10)

You can't really use run numpy without it to be installed first (which
is what the message is about).



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