Replace values in array of indexes corresponding to another array

Question

I have an array A of size [1, x] of values and an array B of size [1, y] (y > x) of indexes corresponding to array

Answer 1

For fetching multiple items operator.itemgetter comes in handy:

from operator import itemgetter
A = [6, 7, 8]
B = [0, 2, 0, 0, 1]

itemgetter(*B)(A)
# (6, 8, 6, 6, 7)

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Also as you've mentioned numpy, this could be done directly by indexing the array as you've specified, i.e. A[B]:

import numpy as np
A = np.array([6, 7, 8])
B = np.array([0, 2, 0, 0, 1])

A[B]
# array([6, 8, 6, 6, 7])

Another option is to use np.take:

np.take(A,B)
# array([6, 8, 6, 6, 7])