reduce、map、zip、filter使用记录

注意：结果取完一次就没了：

# -*- coding:utf-8 -*-


### functools.reduce
from functools import reduce

r1 = reduce(lambda x,y:x+y,[1,2,3,4,5])
print(r1) # 15
r2 = reduce(lambda x,y:x*y,[1,2,3,4,5])
print(r2) # 120

### map
r3 = map(lambda x:x**2,[1,2,3])
print(r3,list(r3)) # <map object at 0x00000155BC0EBC50> [1, 4, 9]
print(list(r3)) # [] —— 取完一次就没得了!

### zip
r4 = zip((1,2,3),("wanghw","naruto","sasuke"))
print(r4,dict(r4)) # <zip object at 0x00000155BC0FAC88> {1: 'wanghw', 2: 'naruto', 3: 'sasuke'}
print(dict(r4)) # {} —— 取完一次就有没得了！
r5 = zip((4,5,6),("whw","naroo","sausu"))
print(r4,list(r5)) # <zip object at 0x00000155BC0FAC88> [(4, 'whw'), (5, 'naroo'), (6, 'sausu')]
print(list(r5)) # [] —— 取完一次就没得了！

### filter
r6 = filter(lambda x:x>2,[1,2,3,4,5])
print(r6,list(r6)) # <filter object at 0x0000022E538E1B38> [3, 4, 5]
print(list(r6)) # [] —— 取完一次就没得了！