python列表推导式

python列表推导式 — 轻量级别循环
list comprehension
利用其它列表创建新列表
python3

[x*x for x in range(10)]
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

[x*x for x in range(10) if x%3 == 0 ]​
[0, 9, 36, 81]


[(x,y) for x in range(3) for y in range(3)]
[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]