如何在Python中深拷贝队列

Question

你好，如何在Python中深拷贝一个队列？谢谢！

Answer 1

你可以用一段简单的代码把一个队列里的成员复制到另一个队列里，代码如下：

# delcare queues 
q1 = queue.Queue()
q2 = queue.Queue()

# perform a deep copy ( copy all elemts from q2 to q1 ) 
while not q2.empty():
         q1.put(q2.get())
         q2.task_done()

Answer 2

我不太清楚你具体需要什么，但你可能会对我在DaniWeb讨论中发布的关于优先队列的代码感兴趣。这个列表很容易通过切片等方式保存副本。

#Python 2.6.5
from random import randint
class Priority:
   def __init__(self,prioritylevels=5):
      """The constructor builds list for priority queue which would be used later
      """
      self.prioritylevels = prioritylevels
      self.pq = [[] for priority in range(self.prioritylevels)] # prioritylevels

   def add_to_queue(self, data, priority=None):
       """Add every received in data and use priority parameter or
         its priority key to get its priority value (1 == highest) in the global queue
       """
       if priority is None: priority = data['priority']-1
       else: priority -= 1

       if 0 <= priority < self.prioritylevels:
             self.pq[priority].append(data)
       else: raise ValueError,"Priority level out of bounds: %s" % priority

   def get(self):
       """ get lowest priority values first from queue """
       for priorityevents in self.pq:
            while priorityevents:
                yield priorityevents.pop(0) ## use list as queue to keep insertion order (remove from front)               
   def num_items(self):
      return sum(len(q) for q in self.pq)


if __name__ == '__main__':

   myqueue = Priority(8)
   for i in range(100000):
      item=randint(0,234234)
      if not i % 10000: print i,
      priority=(item & 0b111) +1 ## lets three lowest bits decide which priority we give
      myqueue.add_to_queue(('Number',item),priority=priority)

   print "\n%i items in queues" % myqueue.num_items()
   print "Items by priorities"
   print '\n'.join("%i: %i" % (priority+1,len(q)) for priority, q in enumerate(myqueue.pq))
   print "\nGetting items out of queue in priority order:"
   priority=0
   for description,i in myqueue.get():
       assert (i & 0b111 >= priority), '** Bug ***' ## validity test priority must be same or lower for items
       priority = i & 0b111 
   # empty after get
   print "Finished"
   print "%i items in queue" % myqueue.num_items()

Answer 3

Python中的queue模块是用来在多个线程之间同步共享数据的。它不是用作数据结构的，并且不支持复制（连浅复制都不行）。

（虽然可以通过使用.get和.put来构造多个深复制的队列，但原来的队列会被销毁。）

如果你想要一个队列（或者栈）作为数据结构，可以使用collections.deque。如果你需要一个优先队列，可以使用heapq模块。deque支持深复制，而heapq是基于列表的，所以也支持深复制。

如何在Python中深拷贝队列

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