Determine the shuffled indices of two lists/arrays

Question

As a challenge, I\'ve given myself this problem:

Given 2 lists, A, and B, where B is a shuffled version of A, the idea is to figure out the shuffled indices.

Answer 1

The numpy_indexed package has an efficient and general solution to this:

import numpy_indexed as npi
result = npi.indices(A, B)

Note that it has a kwarg to set a mode for dealing with missing values; and it works with nd-arrays of any type just the same, as it does with 1d integer arrays.