python开发函数进阶：可迭代的&迭代器&生成器

 1 #!/usr/bin/env python
 2 #_*_coding:utf-8_*_
 3 
 4 # iterator  #迭代器
 5 # iterator   iterable#可迭代对象
 6 l = [1,2,3,4,5]
 7 for i in l:
 8     print(i)
 9 print(iter(l))   #内置函数  iter == l._iter_()
10 l.__iter__()
11 l_iterator = iter(l)
12 print(set(dir(l_iterator))-set(dir(l)))
13 print(next(l_iterator))  #迭代器就要通过next方法取值

 1 #!/usr/bin/env python
 2 #_*_coding:utf-8_*_
 3 
 4 l = [1,2,3,4,5]
 5 l_iterator = iter(l)
 6 print(l_iterator.__next__())
 7 print(l_iterator.__next__())
 8 print(l_iterator.__next__())
 9 print(l_iterator.__next__())
10 print(l_iterator.__next__())
11 next(l_iterator) #==l_iterator.__next__()
12 # while True:  自己写相当于for循环
13 #     try:
14 #         print(next(l_iterator))
15 #     except StopIteration:
16 #         break

1 #!/usr/bin/env python
2 #_*_coding:utf-8_*_
3 
4 from collections import Iterable
5 from collections import Iterator
6 # s = ‘abc‘
7 # print(isinstance(s,Iterable))      s 是不是一个可迭代对象
8 # print(isinstance(s,Iterator))      s 是不是一个迭代对象
9 # print(isinstance(iter(s),Iterator))

 1 #!/usr/bin/env python
 2 #_*_coding:utf-8_*_
 3 
 4 def func():
 5     print(‘aaaa‘)
 6     a = 1
 7     yield a    #返回第一个值
 8     print(‘bbbb‘)
 9     yield 12   #返回第二个值
10 #错误取值，相当于三个新的生成器    
11 # g1 = func()
12 # g2 = func()
13 # g3 = func()
14 # print(next(func() )) #取第一个值
15 # print(next(func() )) #取第二个值
16 # print(next(func() )) #取第三个值 会报错 因为没有第三个值
17 #正确取值，都是同一个生成器
18 # ret = func()  #拿到一个生成器
19 # # print(ret)
20 # print(next(ret)) #取第一个值
21 # print(next(ret)) #取第二个值
22 # print(next(ret)) #取第三个值 会报错 因为没有第三个值

 1 #/usr/bin/env python
 2 #_*_coding:utf-8_*_
 3 
 4 def make_cloth():
 5     for i in range(2000000):
 6         yield "第%s件衣服"%i
 7 # szq = make_cloth()
 8 # print(next(szq))
 9 # print(next(szq))
10 #
11 # print(next(szq))
12 # for i in range(50):
13 #     print(next(szq))

 1 #!/usr/bin/env python
 2 #_*_codingLutf-8_*_
 3 
 4 #监听文件 tail -f
 5 import time
 6 def tail(filename):
 7     with open(filename) as f:
 8         f.seek(0, 2) #从文件末尾算起
 9         while True:
10             line = f.readline()  # 读取文件中新的文本行
11             if not line:
12                 time.sleep(0.1)
13                 continue
14             yield line
15 
16 # for line in tail(‘tmp_file‘):
17 #     print(line,end = ‘‘)

 1 #!/usr/bin/env python
 2 #_*_coding:utf-8_*_
 3 
 4 #7日平均年化收益
 5 def averager():
 6     total = 0
 7     day = 0
 8     avrage = 0
 9     while True:
10         day_num  = yield avrage  #return avrage
11         total += day_num
12         day += 1
13         avrage = total/day
14 
15 # avg = averager()
16 # num = next(avg)  #激活生成器 avg.send(),什么都不send和next效果一样
17 # print(avg.send(10))  #传值 next
18 # print(avg.send(20))

 1 #!/usr/bin/env python
 2 #_*_codingLutf-8_*_
 3 
 4 def wrap(func):
 5     def inner(*args,**kwargs):
 6         g = func(*args,**kwargs)
 7         next(g)
 8         return g
 9     return inner
10 
11 @wrap
12 def averager():
13     total = 0
14     day = 0
15     avrage = 0
16     while True:
17         day_num  = yield avrage  #return avrage
18         total += day_num
19         day += 1
20         avrage = total/day
21 
22 # g = averager()
23 # print(g.send(10))
24 # print(g.send(20))