Python3 生成器

  1 ‘‘‘
  2 列表生成式
  3 ‘‘‘
  4 
  5 # a1 = [x for x in range(10)]
  6 # a2 = [x*2 for x in range(10)]
  7 # print(a1)
  8 # print(a2)
  9 #
 10 # def fun1(x):
 11 #     return x**3
 12 # a3 = [fun1(x) for x in range(10)]
 13 # print(a3)
 14 #
 15 # # 列表生成式
 16 # # 取值方式
 17 # b = [‘asd‘,8,9,10]
 18 # w,x,y,z = b
 19 # print(w,x,y,z)
 20 # print(b)
 21 #
 22 #
 23 # # 生成器
 24 # c = (x*2 for x in range(10))        # c是生成器对象
 25 # print(c)        # <generator object <genexpr> at 0x00000286BEF21CA8>
 26 # # print(next(c))  # 等价于 c.__next__()，在Python2中等价于 c.next()
 27 # # print(next(c))
 28 # # print(next(c))
 29 # # print(next(c))  # 超出范围会报错
 30 #
 31 # # 生成器是可迭代对象
 32 # import time
 33 # for i in c:     # for 对c进行了一个next（）的功能
 34 #     print(i)
 35 #     # time.sleep(1)
 36 
 37 ‘‘‘
 38 生成器的两种创建方式
 39 1.(x*2 for x in range(10))
 40 2.yield
 41 ‘‘‘
 42 
 43 # def fun2():
 44 #     print(‘###‘)    # 此打印没有显示
 45 #     yield 1
 46 # print(fun2())       # fun2()是生成器对象
 47 #
 48 # def fun3():
 49 #     print(‘###‘)
 50 #     yield 1
 51 #
 52 #     print(‘asd‘)
 53 #     yield 2
 54 #
 55 #     return None
 56 #
 57 # c1 = fun3()
 58 # # next(c1)      # next（）被返回1
 59 # # next(c1)      # next（）被返回2
 60 #
 61 # for i in fun3():
 62 #     print(i)    # ‘###’， 1， ‘asd‘, 2
 63 #                 # 此时的1,2是上面的返回值
 64 
 65 
 66 ‘‘‘
 67 什么是可迭代对象,可迭代对象拥有iter方法
 68 ‘‘‘
 69 
 70 # list1 = [1,2,3]
 71 # list1.__iter__()
 72 #
 73 # tup1 = (1,2,3)
 74 # tup1.__iter__()
 75 #
 76 # disc1 = {‘asd‘:123}
 77 # disc1.__iter__()
 78 
 79 
 80 
 81 # # 斐波那契数列
 82 # # 0 1 1 2 3 5 8 13 21 34
 83 # def fun4(max):
 84 #     q,before,after = 0,0,1
 85 #     while q < max:
 86 #         print(after)
 87 #         before,after = after,before+after
 88 #         q += 1
 89 # fun4(10)
 90 # print(fun4(8))
 91 
 92 # # 使用生成器创建斐波那契数列
 93 # def fun5(max):
 94 #     q,before,after = 0,0,1
 95 #     while q < max:
 96 #
 97 #         yield before
 98 #         before,after = after,before+after
 99 #         q = q + 1
100 # z = fun5(8)
101 # print(z)
102 # print(next(z))
103 # print(next(z))
104 # print(next(z))
105 # print(next(z))
106 # print(next(z))
107 
108 
109 ‘‘‘
110 send 方法
111 ‘‘‘
112 # def fun5():
113 #     print(‘a1‘)
114 #     a = yield 1
115 #     print(a)
116 # 
117 #     yield 2
118 # x = fun5()
119 # x1 = x.send(None)       # 等价于next(x)
120 #                         # 第一次send前没有next，只能传一个send（None）
121 # h = x.send(‘aaaaaaaaa‘)
122 # print(h)
123 
124 ‘‘‘
125 send 比 next 多一个功能，是可以传入一个参数给其中的变量
126 
127 ‘‘‘