將for循環行的值映射到元組列表？

Question

對於下面的代碼，我試圖根據列標題列出從行映射到它的元組列表中的值。然而，映射似乎出錯了，並沒有給我我想要的值。

import itertools as it 

def buc(column_headers, tuples): 
    row_dict = {} 
    attribs = [1,2] 
    measure = 10 

    # generate binary table based on number of columns 
    binaries = [i for i in it.product(range(2), repeat=(len(attribs)))] 

    for line in binaries: 
     line = list(line) 

     # replace binary of 1 with 'ALL' or 0 with value from input attribs 
     for index, item in enumerate(line): 
      if (item == 1): 
       line[index] = 'ALL' 
      elif (item == 0): 
       line[index] = attribs[index] 

     line.append(measure) 
     print(line) 

     # map column values to column heading by index and store in row_dict (e.g. {'A': 1, 'B': 'ALL', 'M': 100}) 
     for i in range(len(line)): 
      row_dict[column_headers[i]] = line[i] 
     tuples.append(row_dict) 

    print(tuples) 

下面是電流輸出我得到：

>>> buc(['A', 'B', 'M'], []) 
[1, 2, 10] 
[1, 'ALL', 10] 
['ALL', 2, 10] 
['ALL', 'ALL', 10] 
[{'A': 'ALL', 'B': 'ALL', 'M': 10}, {'A': 'ALL', 'B': 'ALL', 'M': 10}, {'A': 'ALL', 'B': 'ALL', 'M': 10}, {'A': 'ALL', 'B': 'ALL', 'M': 10}] 

正確的輸出我想應該是以下，其中線被正確地映射到元組的基礎上，列標題的索引：

>>> buc(['A', 'B', 'M'], []) 
[1, 2, 10] 
[1, 'ALL', 10] 
['ALL', 2, 10] 
['ALL', 'ALL', 10] 
[{'A': '1', 'B': '2', 'M': 10}, {'A': '1', 'B': 'ALL', 'M': 10}, {'A': 'ALL', 'B': '2', 'M': 10}, {'A': 'ALL', 'B': 'ALL', 'M': 10}] 

我哪裏錯了？

Answer 1

發生這種情況是因爲您的列表tuples只包含對原始字典的引用。請參閱this answer。您可以通過copying該字典解決此問題。

更換

tuples.append(row_dict) 

與

tuples.append(row_dict.copy())