[Numpy-discussion] Proposal: np.search() to complement np.searchsorted()

Stephan Hoyer shoyer at gmail.com
Tue May 9 13:39:09 EDT 2017


On Tue, May 9, 2017 at 9:46 AM, Martin Spacek <numpy at mspacek.mm.st> wrote:

> Looking at my own habits and uses, it seems to me that finding the indices
> of matching values of one array in another is a more common use case than
> finding insertion indices of one array into another sorted array. So, I
> propose that np.search(), or something like it, could be even more useful
> than np.searchsorted().
>

The current version of this PR only returns the indices of the *first*
match (rather than all matches), which is an important detail. I would
strongly consider including that detail in the name (e.g., by calling this
"find_first" rather than "search"), because my naive expectation for a
method called "search" is to find all matches.

In any case, I agree that this functionality would be welcome. Getting the
details right for a high performance solution is tricky, and there is
strong evidence of interest given the 200+ upvotes on this StackOverflow
question:
http://stackoverflow.com/questions/432112/is-there-a-numpy-function-to-return-the-first-index-of-something-in-an-array
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