[Numpy-discussion] index partition

Sebastian Berg sebastian at sipsolutions.net
Sat Apr 12 17:03:45 EDT 2014

On Sa, 2014-04-12 at 16:47 -0400, Alan G Isaac wrote:
>  From a 1d array, I want two arrays of indexes:
> the first for elements that satisfy a criterion,
> and the second for elements that do not.  Naturally
> there are many ways to do this.  Is there a preferred way?
> As a simple example, suppose for array `a` I want
> np.flatnonzero(a>0) and np.flatnonzero(a<=0).
> Can I get them both in one go?

Might be missing something, but I don't think there is a way to do it in
one go. The result is irregularly structured and there are few functions
like nonzero which give something like that.

- Sebastian

> Thanks,
> Alan Isaac
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