>>> a = list(range(10))
>>> b = []
>>> for i in a:
... b.append(i * 10)
...
>>> a
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> b
[0, 10, 20, 30, 40, 50, 60, 70, 80, 90]
>>>
例2 使用 map
>>> mul_ten = lambda x: 10 * x
>>> it = map(mul_ten, [1, 2, 3])
>>> it
<map object at 0x000002AD0F8C00B8>
>>> for i in it:
... print(i)
...
10
20
30
>>>
例3 map 配合 list
>>> a = [1, 2, 3]
>>> b = [4, 5, 6, 7]
>>> list(map(lambda x, y: x + y, a, b)) # 类似 zip
[5, 7, 9]
>>>
例4 map 生成的迭代器只能迭代一次
>>> a = map(lambda x: x * x, [1, 2, 3])
>>> for i in a:
... print(i)
...
1
4
9
>>> for i in a:
... print(i)
...
>>>
>>> b = map(lambda x: x * x, [1, 2, 3])
>>> [i for i in b]
[1, 4, 9]
>>> [i for i in b]
[]
>>>