numpy.intersect1d() function in Python

Last Updated : 17 May, 2020

numpy.intersect1d() function find the intersection of two arrays and return the sorted, unique values that are in both of the input arrays.

Syntax: numpy.intersect1d(arr1, arr2, assume_unique = False, return_indices = False)

Parameters :
arr1, arr2 : [array_like] Input arrays.
assume_unique : [bool] If True, the input arrays are both assumed to be unique, which can speed up the calculation. Default is False.
return_indices : [bool] If True, the indices which correspond to the intersection of the two arrays are returned. The first instance of a value is used if there are multiple. Default is False.

Return : [ndarray] Sorted 1D array of common and unique elements.

Code #1 :

# Python program explaining 
# numpy.intersect1d() function 
     
# importing numpy as geek  
import numpy as geek  
    
arr1 = geek.array([1, 1, 2, 3, 4]) 
arr2 = geek.array([2, 1, 4, 6]) 
    
gfg = geek.intersect1d(arr1, arr2) 
    
print (gfg) 

Output :

[1 2 4]

Code #2 :

# Python program explaining 
# numpy.intersect1d() function 
     
# importing numpy as geek  
import numpy as geek  
    
arr1 = [1, 2, 3, 4, 5, 6, 7, 8, 9] 
arr2 = [1, 3, 5, 7, 9] 
    
gfg = geek.intersect1d(arr1, arr2) 
    
print (gfg) 