How can I “zip sort” parallel numpy arrays?

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b[a.argsort()] should do the trick.

Here’s how it works. First you need to find a permutation that sorts a. argsort is a method that computes this:

>>> a = numpy.array([2, 3, 1])
>>> p = a.argsort()
>>> p
[2, 0, 1]

You can easily check that this is right:

>>> a[p]
array([1, 2, 3])

Now apply the same permutation to b.

>>> b = numpy.array([4, 6, 7])
>>> b[p]
array([7, 4, 6])

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