Question

对于以下代码，我正在尝试打印基于列标题从行映射到它的元组列表中的值。但是，映射似乎出错了，并没有给我我想要的值。

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)

以下是我得到的当前输出：

>>> 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}]

我想要的正确输出应该是以下内容，其中行根据列标题的索引正确映射到元组：

>>> 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}]

我做错了哪里？

Answer 1

这是因为您的列表tuples仅包含对原始字典的引用。见Fiddle demo。您可以通过this answer字典解决此问题。

替换

tuples.append(row_dict)

带

tuples.append(row_dict.copy())

将for-loop行的值映射到元组列表？

1 个答案: