Get list of elements currently in heap using heapq in Python?

Question

This structure i have built for easier understanding and usability

 class PriorityQueue:
    """
      Implements a priority queue data structure.
    """
    def  __init__(self):
        self.heap = []
        self.count = 0

    def push(self, item, priority):
        entry = (priority, self.count, item)
        heapq.heappush(self.heap, entry)
        self.count += 1

    def pop(self):
        (_, _, item) = heapq.heappop(self.heap)
        return item

    def isEmpty(self):
        return len(self.heap) == 0

I want to add a method which will return the list of items currently in this class such that it returns the list elements without the cost without actually popping each and every item

Is there any such way or i have to extract each element

Asked By: Sayan Paul

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Answer 1

Your method could look like this:

def items(self):
    return list(item for _, _, item in self.heap)

This will iterate of the heap and build a new list containing references to the items in the heap without modifying the heap.

Note that if you items are mutable objects, modifying items in the list will also modify the references item in the heap. The may or may not be desirable.

Also note that this list will not be ordered by priority.

Answered By: Ber

Get list of elements currently in heap using heapq in Python?

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