NAME

Array::Heap::PriorityQueue::Numeric - Numeric priority queue

SYNOPSIS

   use Array::Heap::PriorityQueue::Numeric;
   my $pq = Array::Heap::PriorityQueue::Numeric->new();
   $pq->add('fish', 42);
   $pq->add('banana', 27);
   print $pq->get(), "\n"; # banana
   print $pq->peek(), "\n"; # fish

DESCRIPTION

This module implements a priority queue, which is a data structure that can efficiently locate the item with the lowest weight at any time. This is useful for writing cost-minimizing and shortest-path algorithms.

Weights are numeric values.

This module is a wrapper for the *_heap methods provided by Array::Heap.

FUNCTIONS

Array::Heap::PriorityQueue::Numeric->new()

Create a new, empty priority queue.

$pq->add($item, $weight)

Add an item to the priority queue with the given weight. Weight must be numeric, and defaults to item.

$pq->peek()

Return the first (numerically lowest weight) item from the queue. Does not modify the queue. Returns undef if the queue is empty.

$pq->get()

Removes the first item from the priority queue and returns it. Returns undef if the queue is empty. If two items in the queue have equal weight, this module makes no guarantee as to which one will be returned first.

$pq->min_weight()

Returns the weight of the lowest item in the queue, or undef if empty.

$pq->size()

Returns the number of items in the priority queue.

$pq->items()

Returns all items in the heap, in an arbitrary order.

$pq->sorted_items()

Returns all items in the heap, in weight order.

$pq->add_unordered($item, $weight)

Add an item to the priority queue or change its weight, without updating the heap structure. If you are adding a bunch of items at once, it may be more efficient to use add_unordered, then call $pq->restore_order() once you are done. Weight defaults to item.

$pq->restore_order()

Restore the heap structure after calling add_unordered. You need to do this before calling any of the ordered methods (add, peek, or get).

LIMITATIONS

Weights are sorted in increasing order only. If you want it the other way, use the negative of the weights you have.

SEE ALSO

Array::Heap::ModifiablePriorityQueue

AUTHOR

Bob Mathews <bobmathews@alumni.calpoly.edu>

REPOSITORY

https://github.com/bobmath/ModifiablePriorityQueue

COPYRIGHT

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.