将列表列表的列表展平为列表列表

Question

我已经搜索过如何展平列表列表(例如：Making a flat list out of list of lists in Python)，但我发现没有一个解决方案可以将列表列表展平为列表列表。

我有：

my_list = [ [ [1,2,3],[4,5] ], [ [9],[8,9,10],[3,4,6] ], [ [1] ] ]

我想要：

my_list = [ [1,2,3,4,5], [9,8,9,10,3,4,6], [1] ]

这个解决方案也应该适用于浮点数列表。有什么建议吗？

Answer 1

如果我们应用this answer的逻辑，它不应该只是：

In [2]: [[item for subsublist in sublist for item in subsublist] for sublist in my_list]
Out[2]: [[1, 2, 3, 4, 5], [9, 8, 9, 10, 3, 4, 6], [1]]

类似地，通过itertools.chain()

In [3]: [list(itertools.chain(*sublist)) for sublist in my_list]
Out[3]: [[1, 2, 3, 4, 5], [9, 8, 9, 10, 3, 4, 6], [1]]

Answer 2

这是fl00r递归答案的一个由内到外的版本，它更符合OP的意图：

def flatten(lists,n):
    if n == 1:
        return [x for xs in lists for x in xs]   
    else:
        return [flatten(xs,n-1) for xs in lists]


>>> flatten(my_list,1)
[[1, 2, 3], [4, 5], [9], [8, 9, 10], [3, 4, 6], [1]]
>>> flatten(my_list,2)
[[1, 2, 3, 4, 5], [9, 8, 9, 10, 3, 4, 6], [1]]

Answer 3

您可以使用这个递归子例程

def flatten(lst, n):
  if n == 0:
    return lst

  return flatten([j for i in lst for j in i], n - 1)

mylist = [ [ [1,2,3],[4,5] ], [ [9],[8,9,10],[3,4,6] ], [ [1] ] ]
flatten(mylist, 1)
#=> [[1, 2, 3], [4, 5], [9], [8, 9, 10], [3, 4, 6], [1]]
flatten(mylist, 2)
#=> [1, 2, 3, 4, 5, 9, 8, 9, 10, 3, 4, 6, 1]