[Numpy-discussion] Extracting sub-fields from an array as a view (PR 350)

Anthony Scopatz scopatz@gmail....
Sat Jul 14 19:17:28 CDT 2012


+1 for more views.  I agree with Fred about bundling the changes together.

On Sat, Jul 14, 2012 at 6:17 PM, Frédéric Bastien <nouiz@nouiz.org> wrote:

> I think it is better that we bundle those change together. As it is
> done for diagonal, doing it for this case as fine too.
>
> Fred
>
> On Sat, Jul 14, 2012 at 6:31 PM, Travis Oliphant <travis@continuum.io>
> wrote:
> >
> > In  https://github.com/numpy/numpy/pull/350/files ,
> >
> > javius provides a patch to allow field extraction from a structured
> array to
> > return a view instead of a copy.    Generally, this is consistent with
> the
> > desire to have NumPy return views whenever it can.   The same idea
> underlies
> > the change to the diagonal method.
> >
> > Suppose 'myarr' is a structured array with fields ['lat', 'long',
> 'meas1',
> > 'meas2', 'meas3', 'meas4'].
> >
> > Currently,
> >
> > myarr[['lat', 'long', 'mesa3']] will return a copy of the data in the
> > underlying array.   The proposal is to have this return a view, but do
> it in
> > a two-stage approach so that a first version returns a copy with the
> > WARN_ON_WRITE flag set introduced in NumPy 1.7.   A later version will
> > remove the flag (and the copy).
> >
> > What are thoughts on this proposal and which version of NumPy it should
> go
> > in?
> >
> > -Travis
> >
> >
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> >
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