码迷,mamicode.com
首页 > 其他好文 > 详细

迭代器和生成器补充

时间:2017-05-12 22:09:19      阅读:175      评论:0      收藏:0      [点我收藏+]

标签:模拟   ext   迭代器   []   练习   迭代   while   补充   列表   

初步铺垫:

for i in [1,2,3,4]:
pass

l = [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:

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:

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

二级变形:

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__())

三级变形:

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__())

四级变形:(模拟range功能)

def range2():
    start = 0
    while start<10:
        yield start*4
        start += 1

for i in range2():
    print(i)

五级变形:

def range2():
    start = 0
    l = []
    while start<100:
        l.append(start*4)
        start += 1
    return l
print(range2())

六级变形:

def range3():
    start = 0
    while True:
        yield start*4
        start += 1

# print(range3())
for i in range3():
    print(i)

练习之变形计划

练习一:

"1+1+2+3+5..." #斐波那契数列

#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

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)

 

迭代器和生成器补充

标签:模拟   ext   迭代器   []   练习   迭代   while   补充   列表   

原文地址:http://www.cnblogs.com/luchuangao/p/6847081.html

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!