Question

要将列表加载到Python中的队列中，我发现此代码片段无法正常工作。没有项目添加到队列中：

from queue import Queue
my_list = [1,2,3,4,5,6,7,8,9,10]
q = Queue()

# This code doesn't work
map(q.put, my_list)
q.qsize() # Returns zero, which is unexpected

更详细的解决方案：

for num in my_list:
    q.put(num)
print(q.qsize())  # returns 10 as expected

按预期工作。我在这里想念什么？

Answer 1

map(q.put, my_list)仅返回迭代器。除非您进行迭代，否则队列q不会被填充

>>> q = Queue()
>>> itr = map(q.put, my_list)
>>> q.qsize()
0
>>> _ = list(map(q.put, my_list))
>>> q.qsize()
10

Answer 2

map的工作方式不是这样：

delete()

您可以使用ThreadPool获得所需的内容：

from queue import Queue
l = [i for i in range(10)]
q = Queue()
x = map(q.put, l)
q.qsize()
# Output: 0
for _ in x:
    pass
q.qsize()
# Output: 10

如果您需要其他内置功能：

from queue import Queue
from multiprocessing.pool import ThreadPool
l = [i for i in range(10)]
p = ThreadPool()
q = Queue()
_ = p.imap_unordered(q.put, l)
q.qsize()
# Output: 10

Answer 3

我不确定为什么这对您不起作用。也许是您的python版本，我在2.7.6上

from queue import Queue
my_list = [1,2,3,4,5,6,7,8,9,10]
q = Queue()

# This code doesn't work
map(q.put, my_list)
q.qsize()

print q.qsize() # 10

while not q.empty():
    print q.get()

将地图与queue.put（）一起使用？

3 个答案: