[Numpy-discussion] Warnings in numpy.ma.test()

Charles R Harris charlesr.harris at gmail.com
Wed Mar 17 17:43:03 EDT 2010

On Wed, Mar 17, 2010 at 3:13 PM, Darren Dale <dsdale24 at gmail.com> wrote:

> On Wed, Mar 17, 2010 at 4:48 PM, Pierre GM <pgmdevlist at gmail.com> wrote:
> > On Mar 17, 2010, at 8:19 AM, Darren Dale wrote:
> >>
> >> I started thinking about a third method called __input_prepare__ that
> >> would be called on the way into the ufunc, which would allow you to
> >> intercept the input and pass a somehow modified copy back to the
> >> ufunc. The total flow would be:
> >>
> >> 1) Call myufunc(x, y[, z])
> >> 2) myufunc calls ?.__input_prepare__(myufunc, x, y), which returns x',
> >> y' (or simply passes through x,y by default)
> >> 3) myufunc creates the output array z (if not specified) and calls
> >> ?.__array_prepare__(z, (myufunc, x, y, ...))
> >> 4) myufunc finally gets around to performing the calculation
> >> 5) myufunc calls ?.__array_wrap__(z, (myufunc, x, y, ...)) and returns
> >> the result to the caller
> >>
> >> Is this general enough for your use case? I haven't tried to think
> >> about how to change some global state at one point and change it back
> >> at another, that seems like a bad idea and difficult to support.
> >
> >
> > Sounds like a good plan. If we could find a way to merge the first two
> (__input_prepare__ and __array_prepare__), that'd be ideal.
> I think it is better to keep them separate, so we don't have one
> method that is trying to do too much. It would be easier to explain in
> the documentation.
> I may not have much time to look into this until after Monday. Is
> there a deadline we need to consider?
I don't think this should go into 2.0, I think it needs more thought.  And
2.0 already has significant code churn. Is there any reason beyond a big
hassle not to set/restore the error state around all the ufunc calls in ma?
Beyond that, the PEP that you pointed to looks interesting. Maybe some sort
of decorator around ufunc calls could also be made to work.

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