將地圖與queue.put（）一起使用？

Question

要將列表加載到Python中的隊列中，我發現此代碼段無法正常工作。 沒有項目添加到隊列：

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

更詳細的解決方案：

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

可以正常工作。 我在這里想念什么？

Answer 1

map(q.put, my_list)僅返回一個迭代器。 除非您進行迭代，否則不會填充您的隊列q

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

Answer 2

map不是這樣工作的：

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

您可以使用ThreadPool獲得所需的內容：

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

如果您需要其他內置插件：

# list comprehension (essentially what map is equivalent to)
_ = [q.put(i) for i in l]

# the `any` method:
_ = any(q.put(i) for i in l)

Answer 3

我不確定為什么這對您不起作用。 也許您的python版本是2.7.6

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()