Day 21 三元表达式、生成器函数、列表解析

知识点程序:

 #! /usr/bin/env python
 # -*- coding: utf-8 -*-
 # __author__ = "DaChao"
 # Date: 2017/6/16

 l = [i for i in range(100) if i%2 > 0]
 print(l)

 ###########################
 #生成器 generator!!! 模拟tail grep功能
 ###########################

 # import time
 # def tail(filepath,encoding="utf-8"):
 #     with open(filepath,encoding=encoding) as f:
 #         f.seek(0,2)
 #         while True:
 #             line = f.readline()
 #             if line:
 #                 # print("line")
 #                 yield line
 #             else:
 #                 time.sleep(0.5)
 #
 # g = tail("a.txt")
 # for i in g:
 #     print(i)

 # # tail("a.txt")
 # def grep(lines,pattern):
 #     for line in lines:
 #         if pattern in line:
 #             print(line)
 # #

 # # for i in g:
 # #     print(g)
 # g1 = grep(g,"error")
 #
 # g2 = grep(g1,"404")
 # #
 # for line in g2:
 #     print(line)

 ###########################
 #生成器 generator!!! yield 的重复使用
 ###########################

 # def countdown(n):
 #     print("start")
 #     while n > 0:
 #         yield n
 #         n -= 1
 #     print("end")
 #
 # g = countdown(5)

 # print(g)
 # print(g.__next__())
 # print(g.__next__())
 # print(g.__next__())
 # print(g.__next__())
 # print(g.__next__())
 # print(g.__next__())
 #
 # for i in g:
 #     print(i)

 ###########################
 #生成器 带有yield
 ###########################

 # def foo():
 #     print("1111111")
 #     yield 1
 #     print("222222222")
 #     yield 2
 #     print("33333333")
 #     yield 3
 #
 # g = foo()
 #
 # for i in g:       #obj = g.__iter__()  #obj,__next__
 #     print(i)

 # print(g.__next__())
 # print(g.__next__())
 # print(g.__next__())
 # print(g.__next__())
 ###########################
 #生成器函数
 ###########################

 # def lay_eggs(num):
 #     '''
 #     存鸡蛋！
 #     :param num:
 #     :return:
 #     '''
 #     egg_list = []
 #     for egg in range(num):
 #         egg_list.append("egg%s" %egg)
 #     return egg_list

 # yikuangdan = lay_eggs(10)
 # for i in yikuangdan:           #下蛋
 #     print(i)

 # def lay_eggs1(num):
 #     for egg in range(num):
 #         res = "egg%s" %egg
 #         yield res
 #         print("Egg +")
 #
 # laomuji = lay_eggs1(10)
 # print(laomuji)
 # print(laomuji.__next__())
 # print(laomuji.__next__())
 # print(laomuji.__next__())
 # print(laomuji.__next__())
 # egg_l = list(laomuji)
 # print(egg_l)

 ##########################
 #迭代器
 ###########################

 # d = {"a":1,"b":2,"c":3}
 #
 # obj = d.__iter__()
 #
 # while True:
 #     try:
 #         i = obj.__next__()
 #         print(i)
 #     except StopIteration:
 #         break