【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))
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#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
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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+1
print(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
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二级变形：
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def a():
a = 0
while True:
# return a
yield a
a = a+1
l = 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__())
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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 5
l=test2()
print(l.__next__())
print(l.__next__())
print(l.__next__())
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四级变形：（模拟range功能）
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def range2():
start = 0
while start<10:
yield start*4
start += 1
for i in range2():
print(i)
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五级变形：
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def range2():
start = 0
l = []
while start<100:
l.append(start*4)
start += 1
return l
print(range2())
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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)
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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 = c
print(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 = c
l = 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 += 1
l = test3()
print(l.__next__())
print(l.__next__())
print(l.__next__())
for i in l:
print(i)
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