intersection_update() in Python to find common elements in n arrays Last Updated : 21 Jul, 2022 Comments Improve Suggest changes Like Article Like Report We are given list of n number of arrays, find all common elements in given arrays ? Examples: Input : arr = [[1,2,3,4], [8,7,3,2], [9,2,6,3], [5,1,2,3]] Output : Common Elements = [2,3] We can solve this problem quickly in python using intersection_update() method of Set() data structure. How intersection_update() works ? Suppose we have two sets A and B, then A.intersection_update(B) operation updates set A with common elements in set A and B. For example, A=set([1,2,3]) and B=set([4,2,3]) now after taking A.intersection_update(B), value of set A will be [2,3]. Syntax is anySet.intersection_update(iterable). Implementation: Python3 # Function to find common elements in n arrays def commonElements(arr): # initialize result with first array as a set result = set(arr[0]) # now iterate through list of arrays starting from # second array and take intersection_update() of # each array with result. Every operation will # update value of result with common values in # result set and intersected set for currSet in arr[1:]: result.intersection_update(currSet) return list(result) # Driver code if __name__ == "__main__": arr = [[1,2,3,4], [8,7,3,2], [9,2,6,3], [5,1,2,3]] output = commonElements(arr) if len(output) > 0: print ("Common Element = ",output) else: print ('No Common Elements Found') OutputCommon Element = [2, 3] Comment More infoAdvertise with us Next Article intersection_update() in Python to find common elements in n arrays S Shashank Mishra (Gullu) Improve Article Tags : Python DSA Arrays Practice Tags : Arrayspython Similar Reads Python Tutorial | Learn Python Programming Language Python Tutorial – Python is one of the most popular programming languages. It’s simple to use, packed with features and supported by a wide range of libraries and frameworks. 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