python 列表指导式

>>> a=[page for page in range(10)]
>>> print (a)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> a=[page*2 for page in range(10)]
>>> print(a)
[0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
>>> a=[page*2 for page in range(10)if page%2==0]
>>> print(a)
[0, 4, 8, 12, 16]
>>> ab=[x*y for x in range(1,5) if x > 2 for y in range(1,4) if y < 3]
>>> print(ab)
[3, 6, 4, 8]
相当于：
for x in range(1,5):
    if x > 2:
        for y in range(1,4):
            if y < 3:
                print(x*y)==================== RESTART: D:/Python/Python37/dai1.py ====================
3
6
4
8
>>>