map 和 reduce

注意：reduce需要 from functools import reduce

map的使用：

>>> def func(x):
...     return x*x
...
>>> [x for x in range(1,11)]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> l=[x for x in range(1,11)]
>>> l
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> print(map(func,l))
<map object at 0x014E94F0>
>>> ll=list(map(func,l))                #重点用法
>>> ll
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

reduce用法：

>>> l=[i for i in range(1,6)]
>>> l
[1, 2, 3, 4, 5]
>>> def func(x,y):
...     return(x*10+y)
...

>>> reduce(func,l)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name ‘reduce‘ is not defined
                                                             #单个数乘10，组成一个整数
>>> from functools import reduce              #重点
>>> reduce(func,l)                                     #重点
12345

>>> ll=reduce(func,l)
>>> type(ll)
<class ‘int‘>                                            

dd