[Numpy-discussion] Checking for views (was: Should arr.diagonal() return a copy or aview?)

Nathaniel Smith njs at pobox.com
Fri May 25 10:55:01 EDT 2012


On May 25, 2012 2:21 PM, "Robert Kern" <robert.kern at gmail.com> wrote:
>
> On Thu, May 24, 2012 at 5:52 PM, Robert Kern <robert.kern at gmail.com> wrote:
>
> > (Hmm, now that I think about it, the edge cases are when the strides
> > are 0 or negative. 0-stride axes can simply be removed, and I think we
> > should be able to work back to a first item and flip the sign on the
> > negative strides. The typical positive-stride solution can be found in
> > an open source C++ global array code, IIRC. Double-hmmm...)
>
> Except that it's still NP-complete.

Huh, is it really? I'm pretty sure checking the existence of a
solution to a linear Diophantine equation is cheap, but I guess
figuring out whether it falls within the "shape" bounds is less
obvious...

-- Nathaniel



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