結合兩個python列表，並通過密鑰彙總值

Question

我有兩個列表在這裏看到。

a = ['a','b','a'] 
b = [200,300,300] 

當我打印像這樣：

print dict(zip(a,b)) 

我得到：

{'A': 300, 'B': 300} 

我怎麼會集結基於關鍵的值，使我得到

{'A': 500, 'B': 300}？

Answer 1

from collections import Counter 
a = ['a','b','a'] 
b = [200,300,300] 
c = Counter() 
for i, j in zip(a, b): 
    c[i] += j 
print(c) 

Answer 2

result = {} 
for k,v in zip (['a','b','a'], [200,300,300]): 
    result[k] = result.get(k,0) + v 
print result 

Answer 3

一種方式做到這一點是像下面，通過避免拉鍊功能，

aggregateDict = {} 
a= ['a', 'b', 'a'] 
b=[200, 300, 200] 
for i in range(len(a)): 
    aggregateDict[a[i]] = aggregateDict.get(a[i], 0) + b[i] 

輸出將是

{'a': 400, 'b': 300} 

Answer 4

我假設一個清晰的方式（每Python's Zen）實現您的目標是：

from __future__ import print_function 

a = ['a','b','a'] 
b = [200,300,300] 
d = dict() 

for place, key in enumerate(a): 
    try: 
     d[key] += b[place] 
    except KeyError: 
     d[key] = b[place] 
print(d) 

哪個給你的預期輸出：

{ 'A'：500， 'B'：300}

Answer 5

你只需要遍歷的郵政編碼爲鍵和值，並把他們在字典中。

a = ['a','b','a'] 
b = [200,300,300] 

for key, val in zip(a,b): 
    if key in combined_dict: 
     combined_dict[key] += val 
    else: 
     combined_dict[key] = val 

print(combined_dict) 
=> {'a': 500, 'b': 300}