Python程序在字典中查找key代表频率的值的总和

给定一个带有值列表的字典，其中键代表频率，计算值列表中每个值的总出现次数。

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. 

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

这是可以执行此任务的方式。其中，Counter() 用于计算每个值的频率，使用 __add__ 完成与键的求和，使用 reduce() 将每个键的所有值相加。 map() 用于将 Counter 的逻辑扩展到值列表中的每个值。

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)))

输出：

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}