python - 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 A. I want as result an array C of size [1,y] filled with values of A.

Here is an example of inputs and outputs:

>>> A = [6, 7, 8]
>>> B = [0, 2, 0, 0, 1]
>>> C = #Some operations
>>> C
[6, 8, 6, 6, 7]

Of course I could solve it like that:

>>> C = []
>>> for val in B:
>>>     C.append(A[val])

But I was actually expected a nicer way to do it. Especially because I want to use it as an argument of another function. An expression looking like A[B] (but a working one) would be ideal. I don't mind solution using NumPy or pandas.

Answer 1

Simple with a list comprehension:

A = [6, 7, 8]
B = [0, 2, 0, 0, 1]

C = [A[i] for i in B]
print(C)

This yields

[6, 8, 6, 6, 7]