Finding the Indices of multiple items in a list, using a list

Question

I want to essentially use one list ie.

L = [10, 10, 100, 10, 17, 15]

and using another list

R = [10, 15] 

want to return

N = [0, 1, 3, 5] // indices of L that return the values in R

I tried using L.index() to get the indices but that only returns the first value. I then tried running a for loop over L and using L.index(R[0]) every time, but similarly that only returns the first indices it finds at.

 for i in range(len(L)):
       j = R[i]
       N.append(L.index(j))
 return N

This would return index out of range which makes sense, but how do I get it to run through the L?

Answer 1

N = []

for i in range(len(L)):

    if L[i] in R:
        N.append(i)

or with a generator

N = [i for i in range(len(L)) if L[i] in R]

or with arrays

import numpy as np

N=np.where(np.isin(L,R))