如何将混合维度的数组展平为二维列表？

Question

我知道有很多关于如何将二维列表展平的帖子，但这个略有不同，因为它是二维和三维列表的混合：

items = [[255, 204, 204], ..., [255, 179, 179], [[250, 250, 250], ..., [220, 220, 220]]]

我希望这个列表只有两个维度:

items = [[255, 204, 204], ..., [255, 179, 179], [250, 250, 250], ..., [220, 220, 220]]

我尝试使用列表推导式，但是它不能正确地展开列表：

flat_list = [item for items in l for item in items]

什么是将混合维度数组转换为二维数组的最佳方法？

- Hiroyuki Nuri

Answer 1

old_list = [[255, 204, 204], [255, 179, 179], [['250, 250, 250'], ['220, 220, 220']]]                                                                                                         
new_list = []  
for i in old_list:
    if isinstance(i[0], list):
        for j in i:
            new_list.append(j)
    else:
        new_list.append(i)
print new_list

输出结果为：

[[255, 204, 204], [255, 179, 179], ['250, 250, 250'], ['220, 220, 220']]

- GuangshengZuo

Answer 2

您可以使用递归函数：

def flatten(items):
    for item in items:
        if isinstance(item[0], list):
            yield from flatten(item)
        else:
            yield item

示例：

>>> items = [[255, 204, 204], [255, 179, 179], [['250, 250, 250'], ['220, 220, 220']]]
>>> list(flatten(items))
[[255, 204, 204], [255, 179, 179], ['250, 250, 250'], ['220, 220, 220']]

- Eugene Yarmash

Answer 3

from itertools import chain

items = [[255, 204, 204], [255, 179, 179], [['250, 250, 250'], ['220, 220, 220']]]

flat_list = list(chain.from_iterable(lst if isinstance(lst[0], list) else [lst] for lst in items))

print(flat_list)
>>> [[255, 204, 204], [255, 179, 179], ['250, 250, 250'], ['220, 220, 220']]

- jdehesa

Answer 4

def tree2matrix(T):
  if T == []:
    return []
  elif type(T) is not list:
    return [[T]]
  elif type(T[0]) is not list:
    return [T]
  else:
    return tree2matrix(T[0]) + tree2matrix(T[1:])

X = [[255, 204, 204], [255, 179, 179], [['250, 250, 250'], ['220, 220, 220']]]
print(tree2matrix(X))

- englealuze