You can use the setdiff1d() function of Numpy that returns elements in array1 that are not in array2. Here is an example:
>>> import numpy as np>>> a=np.array([11,12,13,14,15])>>> b=np.array([14,15,16,17,18])>>> np.setdiff1d(a, b)array([11, 12, 13])>>> np.setdiff1d(b, a)array([16, 17, 18])