Day 21 三元表达式、生成器函数、列表解析

知识点程序:

  1 #! /usr/bin/env python
  2 # -*- coding: utf-8 -*-
  3 # __author__ = "DaChao"
  4 # Date: 2017/6/16
  5
  6 l = [i for i in range(100) if i%2 > 0]
  7 print(l)
  8
  9 ###########################
 10 #生成器 generator!!! 模拟tail grep功能
 11 ###########################
 12
 13 # import time
 14 # def tail(filepath,encoding="utf-8"):
 15 #     with open(filepath,encoding=encoding) as f:
 16 #         f.seek(0,2)
 17 #         while True:
 18 #             line = f.readline()
 19 #             if line:
 20 #                 # print("line")
 21 #                 yield line
 22 #             else:
 23 #                 time.sleep(0.5)
 24 #
 25 # g = tail("a.txt")
 26 # for i in g:
 27 #     print(i)
 28
 29 # # tail("a.txt")
 30 # def grep(lines,pattern):
 31 #     for line in lines:
 32 #         if pattern in line:
 33 #             print(line)
 34 # #
 35
 36 # # for i in g:
 37 # #     print(g)
 38 # g1 = grep(g,"error")
 39 #
 40 # g2 = grep(g1,"404")
 41 # #
 42 # for line in g2:
 43 #     print(line)
 44
 45 ###########################
 46 #生成器 generator!!! yield 的重复使用
 47 ###########################
 48
 49 # def countdown(n):
 50 #     print("start")
 51 #     while n > 0:
 52 #         yield n
 53 #         n -= 1
 54 #     print("end")
 55 #
 56 # g = countdown(5)
 57
 58 # print(g)
 59 # print(g.__next__())
 60 # print(g.__next__())
 61 # print(g.__next__())
 62 # print(g.__next__())
 63 # print(g.__next__())
 64 # print(g.__next__())
 65 #
 66 # for i in g:
 67 #     print(i)
 68
 69
 70
 71 ###########################
 72 #生成器 带有yield
 73 ###########################
 74
 75 # def foo():
 76 #     print("1111111")
 77 #     yield 1
 78 #     print("222222222")
 79 #     yield 2
 80 #     print("33333333")
 81 #     yield 3
 82 #
 83 # g = foo()
 84 #
 85 # for i in g:       #obj = g.__iter__()  #obj,__next__
 86 #     print(i)
 87
 88 # print(g.__next__())
 89 # print(g.__next__())
 90 # print(g.__next__())
 91 # print(g.__next__())
 92 ###########################
 93 #生成器函数
 94 ###########################
 95
 96 # def lay_eggs(num):
 97 #     ‘‘‘
 98 #     存鸡蛋！
 99 #     :param num:
100 #     :return:
101 #     ‘‘‘
102 #     egg_list = []
103 #     for egg in range(num):
104 #         egg_list.append("egg%s" %egg)
105 #     return egg_list
106
107 # yikuangdan = lay_eggs(10)
108 # for i in yikuangdan:           #下蛋
109 #     print(i)
110
111 # def lay_eggs1(num):
112 #     for egg in range(num):
113 #         res = "egg%s" %egg
114 #         yield res
115 #         print("Egg +")
116 #
117 # laomuji = lay_eggs1(10)
118 # print(laomuji)
119 # print(laomuji.__next__())
120 # print(laomuji.__next__())
121 # print(laomuji.__next__())
122 # print(laomuji.__next__())
123 # egg_l = list(laomuji)
124 # print(egg_l)
125
126
127 ##########################
128 #迭代器
129 ###########################
130
131 # d = {"a":1,"b":2,"c":3}
132 #
133 # obj = d.__iter__()
134 #
135 # while True:
136 #     try:
137 #         i = obj.__next__()
138 #         print(i)
139 #     except StopIteration:
140 #         break