python - 如何简化python中的两个嵌套循环

Question

我试图在 python 中简化两个需要的 for 循环，但我无法解决这个问题。我的代码：

head = [[1, 2], [3, 4]]
temp = []
for array in head:
    for element in array:
        temp.append(element)
print(temp)
========OUTPUT========
[1, 2, 3, 4]

我尝试：

head = [[1, 2], [3, 4]]
temp = []
for array in head:
   temp += [element for element in array]
print(temp)

但只能简化一个循环

编辑：解决方案

@serafeim 针对我的案例的具体解决方案：

head = [[1, 2], [3, 4]]
print([element for array in head for element in array])

其他解决方案：

通过匿名

from functools import reduce
head = [[1, 2], [3, 4]]
print(reduce(list.__add__, head))

作者：@chepner

from itertools import chain
head = [[1, 2], [3, 4]]
print([x for x in chain.from_iterable(head)])

作者：@R-zu

import numpy as np
head = [[1, 2], [3, 4]]
print(np.array(head).reshape(-1).tolist())

标签： pythonarrayslistloopsfor-loop

Answer 1

在某些情况下，n 维数组比列表更好。

import numpy as np
x = np.array([[1, 2], [3, 4]]) 
print(x.reshape(-1))
print(x.reshape(-1).tolist())