python学习之老男孩python全栈第九期_day014作业

0. 默写
a. 生成器函数
获取移动平均值例子：

 1 def init(func):
 2     def inner(*args,**kwargs):
 3         ret = func(*args,**kwargs)
 4         ret.__next__()
 5         return ret
 6     return inner
 7 @init
 8 def average():
 9     average = 0
10     count = 0
11     sum = 0
12     while 1:
13         num = yield average
14         sum += num
15         count += 1
16         average = sum/count
17 ret = average()
18 print(ret.send(10))
19 print(ret.send(20))

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b. 生成器表达式

egg = ('鸡蛋%s'%i for i in range(10))
for i in egg:
    print(i)

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作业

1. 通读迭代器生成器博客，将所有实例都敲一次，务必把代码的执行过程搞明白

2. 处理文件：用户指定要查找的文件和内容
将文件中包含要查找内容的每一行都输出到屏幕

1 def check_file():
2     with open('a.txt',encoding='utf-8') as f:
3         for i in f:
4             if 'KID' in i:
5                 yield i
6 g = check_file()
7 for i in g:
8     print(i)

3. 写生成器，从文件中读取内容，在每一次读取到的内容之前加上‘***’之后再返回用户

1 def read_file():
2     with open('a.txt',encoding='utf-8') as f:
3         for i in f:
4             yield '***' + i
5 r = read_file()
6 for i in r:
7     print(i)

推导式练习题：

1. 过滤掉长度小于3的字符串列表，并将剩下的转换成大写字母

1 li = ['qwer','asdf','zxcv','ty','gh','bn','uIo','UIj','plm']
2 lis = [i.upper() for i in li if len(i) >= 3]
3 print(lis)

2. 求(x,y)其中x是0-5之间的偶数，y是0-5之间的奇数组成的元祖列表

lis = [(x,y) for x in range(0,6,2) for y in range(1,6,2)]
print(lis)

3. 求M中3,6,9组成的列表M = [[1,2,3],[4,5,6],[7,8,9]]

M = [[1,2,3],[4,5,6],[7,8,9]]
lis = [i[2] for i in M]
print(lis)