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我相信我犯了一个我找不到的小错误。基本上,我正在设计一个简单的数据容器来保存{key1:[values1],key2:[values2]}。

class Cells(object):
    def __init__(self, **kwargs):
        self.data = {}

    def __data_len__(self):
        """ Length of data[first key] list. """
        _ = 0
        for key in self.data.keys():
            if self.data[key]:
                _ = len(self.data[key])
                break
        return _

    def subtract_lists(self, x, y):
        return [item for item in x if item not in y]

    def add(self, to_add):
        """ Add columns if not exist """
        if not set(to_add.keys()).issubset(self.data.keys()):       # New key means adding
            new_keys = self.subtract_lists(to_add.keys(), \
                                            self.data.keys())       # it to our dict
            newdict = dict.fromkeys(new_keys, \
                                    [] * self.__data_len__())
            self.data.update(newdict)

        [self.data[key].append(to_add.get(key, '')) for key in self.data.keys()]
        print('* Updated data is: %s' % self.data)

##############################
# Now, tests...              #
##############################
if __name__ == '__main__':
    cells = Cells()
    cells.add({'one':1, 'two':2, 'three': 3})

预期输出如下:

Updated data is: {'one': [1], 'two': [2], 'three': [3]}

但它输出:

Updated data is: {'one': [1, 2, 3], 'two': [1, 2, 3], 'three': [1, 2, 3]}