[Numpy-discussion] Include last element when subindexing numpy arrays?

Robert Kern robert.kern at gmail.com
Wed Aug 31 08:42:07 EDT 2016


On Wed, Aug 31, 2016 at 1:34 PM, Matti Viljamaa <mviljamaa at kapsi.fi> wrote:
>
> On 31 Aug 2016, at 15:22, Robert Kern <robert.kern at gmail.com> wrote:
>
> On Wed, Aug 31, 2016 at 12:28 PM, Matti Viljamaa <mviljamaa at kapsi.fi>
wrote:
> >
> > Is there a clean way to include the last element when subindexing numpy
arrays?
> > Since the default behaviour of numpy arrays is to omit the “stop index”.
> >
> > So for,
> >
> > >>> A
> > array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
> > >>> A[0:5]
> > array([0, 1, 2, 3, 4])
>
> A[5:]
>
> --
> Robert Kern
>
> No that returns the subarray starting from index 5 to the end.
>
> What I want to be able to return
>
> array([0, 1, 2, 3, 4, 5])
>
> (i.e. last element 5 included)
>
> but without the funky A[0:6] syntax, which looks like it should return
>
> array([0, 1, 2, 3, 4, 5, 6])
>
> but since bumpy arrays omit the last index, returns
>
> array([0, 1, 2, 3, 4, 5])
>
> which syntactically would be more reasonable to be A[0:5].

Ah, I see what you are asking now.

The answer is "no"; this is just the way that slicing works in Python in
general. numpy merely follows suit. It is something that you will get used
to with practice. My sense of "funkiness" and "reasonableness" is the
opposite of yours, for instance.

--
Robert Kern
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