python common elements in two arrays

1len([x for x in list1 if x in list2])

1# using numpy
2import numpy as np
3a = np.array([1,2,3,2,3,4,3,4,5,6])
4b = np.array([7,2,10,2,7,4,9,4,9,8])
5# using intersect1d
6print(np.intersect1d(a,b))
7# output
8# [2 4]

1x = {2, 3, 5, 6}
2y = {1, 2, 3, 4}
3
4z = x.intersection(y)
5