Count distinct elements in an array in Python

Given an unsorted array, count all distinct elements in it.


Input : arr[] = {10, 20, 20, 10, 30, 10} 
Output : 3

Input : arr[] = {10, 20, 20, 10, 20}
Output : 2

We have existing solution for this article. We can solve this problem in Python3 using Counter method.





from collections import Counter
def countDistinct(arr):
    # counter method gives dictionary of elements in list
    # with their corresponding frequency.
    # using keys() method of dictionary data structure
    # we can count distinct values in array
    return len(Counter(arr).keys())    
if __name__=="__main__":
    arr = [10, 20, 20, 10, 30, 10]
    print (countDistinct(arr))


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