[Numpy-discussion] Proposal: np.search() to complement np.searchsorted()
numpy at mspacek.mm.st
Tue May 9 12:46:25 EDT 2017
I've opened up a pull request to add a function called np.search(), or something
like it, to complement np.searchsorted():
There's also this issue I opened before starting the PR:
Proposed API changes require discussion on the list, so here I am!
This proposed function (and perhaps array method?) does the same as
np.searchsorted(a, v), but doesn't require `a` to be sorted, and explicitly
checks if all the values in `v` are a subset of those in `a`. If not, it
currently raises an error, but that could be controlled via a kwarg.
As I mentioned in the PR, I often find myself abusing np.searchsorted() by not
explicitly checking these assumptions. The temptation to use it is great,
because it's such a fast and convenient function, and most of the time that I
use it, the assumptions are indeed valid. Explicitly checking those assumptions
each and every time before I use np.searchsorted() is tedious, and easy to
forget to do. I wouldn't be surprised if many others abuse np.searchsorted() in
the same way.
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().
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