Count frequencies of all elements in array in Python using collections module
Given an unsorted array of n integers which can contains n integers. Count frequency of all elements that are present in array.
Examples:
Input : arr[] = [1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 4, 5, 5]
Output : 1 -> 4
2 -> 4
3 -> 2
4 -> 1
5 -> 2
This problem can be solved in many ways, refer Count frequencies of all elements in array link. In Python, we can quickly solve this problem in using Collections module.
# Function to count frequency of each element import collections # it returns a dictionary data structure whose # keys are array elements and values are their # corresponding frequencies {1: 4, 2: 4, 3: 2, # 5: 2, 4: 1} def CountFrequency(arr): return collections.Counter(arr) # Driver function if __name__ == "__main__": arr = [1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 4, 5, 5] freq = CountFrequency(arr) # iterate dictionary named as freq to print # count of each element for key, value in freq.iteritems(): print key, " -> ", value |
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Output:
1 -> 4 2 -> 4 3 -> 2 4 -> 1 5 -> 2
Related Article :
Counting the frequencies in a list using dictionary in Python
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