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Python program to find the sum of the value in the dictionary where the key represents the frequency

  • Last Updated : 01 Oct, 2020

Given a dictionary with a values list, where the key represents frequency, compute the total occurrence of each value in values lists.

Input : test_dict = {70 : [7, 4, 6], 50 : [6, 8, 5, 2]} 
Output : {7: 70, 4: 70, 6: 120, 8: 50, 5: 50, 2: 50} 
Explanation : 6 occurs in both keys, hence 70 + 50 = 120, assigned to 6.

Input : test_dict = {70 : [7, 4], 50 : [6, 8, 5, 2]} 
Output : {7: 70, 4: 70, 6: 50, 8: 50, 5: 50, 2: 50} 
Explanation : 6 now occurs in only 50 key, hence only 50 is assigned. 

Method : reduce() + Counter() + lambda + __add__

This is the way in which this task can be performed. In this, Counter() is used to compute the frequency of each value, the summation with keys is done using __add__, all the values from each key are added using reduce(). The map() is used to extend the logic of Counter to each value in the values list.



Python3




# Python3 code to demonstrate working of 
# Frequency Key Values Summation
# Using reduce() + Counter() + lambda + __add__
from functools import reduce
from collections import Counter
  
# initializing dictionary
test_dict = {70 : [7, 4, 6], 
             100 : [8, 9, 5], 
             200 : [2, 5, 3, 7], 
             50 : [6, 8, 5, 2]}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Counter() used to get values mapped with keys 
# __add__ used to add key with values.
res = reduce(Counter.__add__, map(lambda sub: Counter({ele : sub[0] for ele in sub[1]}), 
                    test_dict.items()) )
# printing result 
print("Extracted Summation dictionary : " + str(dict(res))) 

Output:

The original dictionary is : {70: [7, 4, 6], 100: [8, 9, 5], 200: [2, 5, 3, 7], 50: [6, 8, 5, 2]}
Extracted Summation dictionary : {7: 270, 4: 70, 6: 120, 8: 150, 9: 100, 5: 350, 2: 250, 3: 200}

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