python 平摊列表

>>> a = [[1, 2], [3, 4], [5, 6]]

>>> import itertools


>>> list(itertools.chain.from_iterable(a))

[1, 2, 3, 4, 5, 6]

 

>>> sum(a, [])

[1, 2, 3, 4, 5, 6]

 

>>> [x for l in a for x in l]

[1, 2, 3, 4, 5, 6]

 

>>> a = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]]

>>> [x for l1 in a for l2 in l1 for x in l2]

[1, 2, 3, 4, 5, 6, 7, 8]

 

>>> a = [1, 2, [3, 4], [[5, 6], [7, 8]]]

>>> flatten = lambda x: [y for l in x for y in flatten(l)] if type(x) is list else [x]

>>> flatten(a)

[1, 2, 3, 4, 5, 6, 7, 8]

 

注意: 根据Python的文档，itertools.chain.from_iterable是首选。