生成器进阶

Posted 2021-01-21 20181013python

def generator():
    print(123)
    content = yield 1
    print(‘=======‘,content)
    print(456)
    arg = yield 2
    ‘‘‘‘‘‘
    yield
g1 = generator()
g2 = generator()
g1.__next__()
g2.__next__()
print(‘***‘,generator().__next__())
print(‘***‘,generator().__next__())

g = generator()
ret = g.__next__()
print(‘***‘,ret)
ret = g.send(‘hello‘)   #send的效果和next一样
print(‘***‘,ret)

#send 获取下一个值的效果和next基本一致
#只是在获取下一个值的时候，给上一yield的位置传递一个数据
#使用send的注意事项
    # 第一次使用生成器的时候 是用next获取下一个值
    # 最后一个yield不能接受外部的值

# 获取移动平均值
# 10 20 30 10
# 10 15 20 17.5
avg = sum/count
def average():
    sum = 0
    count = 0
    avg = 0
    while True:
        num = yield avg
        sum += num    # 10
        count += 1    # 1
        avg = sum/count

avg_g = average()
avg_g.__next__()
avg1 = avg_g.send(10)
avg1 = avg_g.send(20)
print(avg1)

#预激生成器的装饰器
def init(func):   #装饰器
    def inner(*args,**kwargs):
        g = func(*args,**kwargs)    #g = average()
        g.__next__()
        return g
    return inner

@init
def average():
    sum = 0
    count = 0
    avg = 0
    while True:
        num = yield avg
        sum += num    # 10
        count += 1    # 1
        avg = sum/count

avg_g = average()   #===> inner
ret = avg_g.send(10)
print(ret)
ret = avg_g.send(20)
print(ret)

#python 3
# def generator():
#     a = ‘abcde‘
#     b = ‘12345‘
#     for i in a:
#         yield i
#     for i in b:
#         yield i
def generator():
    a = ‘abcde‘
    b = ‘12345‘
    yield from a
    yield from b

g = generator()
for i in g:
    print(i)

# send
    # send的作用范围和next一模一样
    # 第一次不能用send
    # 函数中的最后一个yield不能接受新的值

# 计算移动平均值的例子
# 预激生成器的装饰器的例子
# yield from