【迭代器与生成器补充】
初步铺垫：
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for i in [1,2,3,4]:passl = [1,2,3,4]l2 = iter(l)print(l2.__next__())print(l2.__next__)print(range(100)) #range(100) 就是一个生成器，为了节省内存，值不会直接输出print(range(0,100)) |
#两种range取值方法：
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print(list(range(100))) #通过列表for i in range(100): #通过for循环 print(i)print(list(range(1,100,2))) #步长 |
生成器变形计划：
一级变形：
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def a(): a = 0 while True: # return a yield a a = a+1print(a().__next__())print(a().__next__()) #全是0,每次重新执行那个函数，这个函数就会重新执行 |
二级变形：
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def a(): a = 0 while True: # return a yield a a = a+1l = a()print(l)print(l.__next__()) #next可以递归的取值，是因为l始终指得是一个函数print(l.__next__())print(l.__next__()) |
三级变形：
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def test2(): # for i in range(1,6): # yield i #冻结 yield 1 yield 2 yield 3 yield 4 yield 5l=test2()print(l.__next__())print(l.__next__())print(l.__next__()) |
四级变形：（模拟range功能）
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def range2(): start = 0 while start<10: yield start*4 start += 1for i in range2(): print(i) |
五级变形：
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def range2(): start = 0 l = [] while start<100: l.append(start*4) start += 1 return lprint(range2()) |
六级变形：
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def range3(): start = 0 while True: yield start*4 start += 1# print(range3())for i in range3(): print(i) |
练习变形计划
练习一：
"1+1+2+3+5..." #斐波那契数列
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#初步：def test(): a,b = 1,1 while a<10: c = a + b yield c a = b b = cprint(test())l = test()print(l.__next__())print(l.__next__())for i in l: print(i)#终极：def test4(): a = 1 yield a b = 1 yield b while True: c = a+b yield c a = b b = cl = test4()print(l.__next__())print(l.__next__())print(l.__next__())print(l.__next__())print(l.__next__())# for i in l:# print(i) |
练习二：
母鸡下蛋例子
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def test3(): i = 0 while i < 10: yield '母鸡下了个蛋,这是第%s个蛋'%(i+1) i += 1l = test3()print(l.__next__())print(l.__next__())print(l.__next__())for i in l: print(i)
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