How to do List flattening inside the loop with list comprehension?
这里我有一个字典列表，我的目标是遍历列表，每当有两个或更多的列表可用时，我希望合并它们并追加到一个输出列表中，每当只有一个列表时，需要将其存储为它的形式。
1 2 3 4 5 6 | 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
1 2 | print([item for sublist in data[0] for item in sublist]) [{'font-weight': '1'}, {'font-weight': '1'}, {'font-weight': '2'}, {'font-weight': '2'}] |
号
预期输出：
1 2 3 4 5 6 | 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'}] ] |
对于那些需要扁平化的元素，可以将条件列表理解与
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | 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'}]] |
试试这个，
1 2 3 | result = [] for item in data: result.append([i for j in item for i in j]) |
具有列表理解功能的单行代码，
1 | [[i for j in item for i in j] for item in data] |
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替代方法，
1 2 | import numpy as np [list(np.array(i).flat) for i in data] |
结果
1 2 3 4 5 6 7 8 9 10 | [[{'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'}]] |
。
遍历列表并检查每个项是否是列表列表。如果是这样，把它压平。
1 2 3 4 5 6 7 8 9 10 11 | 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'}] ] for n, each_item in enumerate(data): if any(isinstance(el, list) for el in each_item): data[n] = sum(each_item, []) print data |
。