# Find the indicies for a certain value within a list np.where(list == 1) see https://stackoverflow.com/questions/6294179/how-to-find-all-occurrences-of-an-element-in-a-list # Return list values in indices specified in a list if just a list, use list comprehension a = [-2,1,5,3,8,5,6] b = [1,2,5] c = [ a[i] for i in b] you can use numpy a = np.array([-2, 1, 5, 3, 8, 5, 6]) b = [1, 2, 5] print(list(a[b])) see https://stackoverflow.com/questions/18272160/access-multiple-elements-of-list-knowing-their-index