python - 如何使用列表理解在循环内进行列表展平？

Question

这里我有字典列表，我的目标是遍历列表，只要有 2 个或更多列表可用，我想合并它们并附加到输出列表中，只要只有一个列表，它就需要原样存储。

data = [
            [[{'font-weight': '1'},{'font-weight': '1'}],[{'font-weight': '2'},{'font-weight': '2'}]],
            [{'font-weight': '3'},{'font-weight': '3'},{'font-weight': '3'}],
            [[{'font-weight': '1'},{'font-weight': '1'}],[{'font-weight': '2'},{'font-weight': '2'}]],
            [{'font-weight': '3'},{'font-weight': '3'}]
        ]

我可以对特定元素 data[0] 进行列表展平

print([item for sublist in data[0] for item in sublist])
[{'font-weight': '1'}, {'font-weight': '1'}, {'font-weight': '2'}, {'font-weight': '2'}]

预期输出:

data = [
            [{'font-weight': '1'},{'font-weight': '1'},{'font-weight': '2'},{'font-weight': '2'}],
            [{'font-weight': '3'},{'font-weight': '3'},{'font-weight': '3'}],
            [{'font-weight': '1'},{'font-weight': '1'},{'font-weight': '2'},{'font-weight': '2'}]
            [{'font-weight': '3'},{'font-weight': '3'}]
        ]

Answer 1

你可以使用 conditional list comprehension与 itertools.chain对于那些需要展平的元素:

In [54]: import itertools

In [55]: [list(itertools.chain(*l)) if isinstance(l[0], list) else l for l in data]
Out[55]: 
[[{'font-weight': '1'},
  {'font-weight': '1'},
  {'font-weight': '2'},
  {'font-weight': '2'}],
 [{'font-weight': '3'}, {'font-weight': '3'}, {'font-weight': '3'}],
 [{'font-weight': '1'},
  {'font-weight': '1'},
  {'font-weight': '2'},
  {'font-weight': '2'}],
 [{'font-weight': '3'}, {'font-weight': '3'}]]