如何遍历优先队列? [英] How to iterate over a Priority Queue?

问题描述

我正在尝试在 Python 中实现 Uniform-cost search那，我需要一个优先级队列，我正在使用 queue.py来自标准库.但是，算法的末尾会检查队列中是否存在任何成本较高的路径.如果它不可迭代，我如何检查我的队列中是否有任何给定的值?

解决方案

queue.PriorityQueue 实际上是使用 list 实现的，put>/get 方法使用 heapq.heappush/heapq.heappop 来维护 list 中的优先级排序.因此，如果您愿意，您可以遍历包含在 queue 属性中的内部列表:

<预><代码>>>>从队列导入PriorityQueue>>>q = PriorityQueue()>>>q.put((5, "a"))>>>q.put((3, "b"))>>>q.put((25, "c"))>>>q.put((2, "d"))>>>打印(q.queue)[(2, 'd'), (3, 'b'), (25, 'c'), (5, 'a')]

I'm trying to implement the Uniform-cost search in Python and for that, I need a priority queue, which I'm using queue.py from the standard library. However, the end of the algorithm checks if there is any path with a higher cost in the queue. How can I check if there is any given value in my queue if it's not iterable?

解决方案

queue.PriorityQueue is actually implemented using a list, and the put/get methods use heapq.heappush/heapq.heappop to maintain the priority ordering inside that list. So, if you wanted to, you could just iterate over the internal list, which is contained in the queue attribute:

>>> from queue import PriorityQueue
>>> q = PriorityQueue()
>>> q.put((5, "a"))
>>> q.put((3, "b"))
>>> q.put((25, "c"))
>>> q.put((2, "d"))
>>> print(q.queue)
[(2, 'd'), (3, 'b'), (25, 'c'), (5, 'a')]

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