python 如何将a = [[1,2,3], [4,5,6], [7,8,9]]列表中的元素变成a=[1,2,3,4,5,6,7,8,9]

Question

最好用for 循环 谢谢

Answer 1

a = [[1,2,3], [4,5,6], [7,8,9]]
b = []
for i in a:
    for j in i:
        b.append(j)
a = b

上面的代码就可以完成转换

Answer 2

方法1:
>>> a = [[1,2,3], [4,5,6], [7,8,9]]
>>> a=[num for elem in a for num in elem]
>>> a
[1, 2, 3, 4, 5, 6, 7, 8, 9]
方法2:
>>> a = [[1,2,3], [4,5,6], [7,8,9]]
>>> a= sum(a,[])
>>> a
[1, 2, 3, 4, 5, 6, 7, 8, 9]
方法3:
>>> a = [[1, 2, 3],[4, 5,6],[7,8,9]]
>>> from itertools import chain
>>> a =list(chain(*a))
>>> a
[1, 2, 3, 4, 5, 6, 7, 8, 9]