python - 如何添加键值而不是替换它们。 Python 字典

Question

1st Text file format . 
cake,60
cake,30
tart,50
bread,89  

2nd Text file format . 
cake,10
cake,10
tart,10
bread,10  

我尝试过的代码。

from collections import defaultdict
answer = defaultdict(int)
recordNum = int(input("Which txt files do you want to read from "))
count = 1
counter = 0
counst = 1
countesr = 0
while recordNum > counter:
  with open('txt'+str(count)+'.txt', 'r') as f:
      for line in f:
          k, v = line.strip().split(',')
          answer[k.strip()] += int(v.strip())
          count = count+1
          counter = counter+1
print(answer)

问题。

I want the dictionary to be {'cake': '100', 'tart': '60', 'bread': '99'}

but it prints like this  {'cake': '30', 'tart': '50', 'bread': '89'}

“蛋糕”值不是与 txt 文件一和二中的其他蛋糕值相加，而是被替换为最新值。我该如何解决这个问题。

Answer 1

您可以使用collections.defaultdict累积计数:

from collections import defaultdict

answer = defaultdict(int)
with open("file.txt", 'r') as f:
    for line in f:
        k, v = line.split(',')
        answer[k.strip()] += int(v.strip())

# turn values back to string
for k in answer:
    answer[k] = str(answer[k])
print(answer)

如果计数均为正数，您可以考虑使用collections.Counter。