how to find out what elements two arrays share in python code example

Example 1: find number of common element in two python array

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

Example 2: python common elements in two arrays

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