Python產生器的經典程式

標籤：

import random def get_data():    """返回0到9之間的3個隨機數"""    return random.sample(range(10), 3) def consume():    """顯示每次傳入的整數列表的動態平均值"""    running_sum = 0    data_items_seen = 0     while True:        data = yield        data_items_seen += len(data)        running_sum += sum(data)        print(‘The running average is {}‘.format(running_sum / float(data_items_seen))) def produce(consumer):    """產生序列集合，傳遞給消費函數（consumer）"""    while True:        data = get_data()        print(‘Produced {}‘.format(data))        consumer.send(data)        yield if __name__ == ‘__main__‘:    consumer = consume()#啟動產生器    consumer.send(None)    producer = produce(consumer)     for _ in range(10):        print(‘Producing...‘)        next(producer)

對比：yield作為語句還是運算式。

import random def get_data():    """返回0到9之間的3個隨機數"""    return random.sample(range(10), 3) def consume(data):    """顯示每次傳入的整數列表的動態平均值"""    running_sum = 0    data_items_seen = 0     while True:        data = yield data        """內部掛起產生器，yield作為運算式而不是語句"""        """產生器運行時，yield返回一個值，就是外部通過send方法發送的值"""        data_items_seen += len(data)        running_sum += sum(data)        print(‘The running average is {}‘.format(running_sum / float(data_items_seen))) def produce(consumer):    """產生序列集合，傳遞給消費函數（consumer）"""    while True:        data = get_data()        print(‘Produced {}‘.format(data))        consumer.send(data)        yield if __name__ == ‘__main__‘:    consumer = consume(0)    consumer.send(None)    producer = produce(consumer)     for _ in range(10):        print(‘Producing...‘)        next(producer)

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Python產生器的經典程式