I stuck to the textbook convention, but using the sink/swim nomenclature from Sedgewick et al: the way I like to think of it, an item that is too "heavy" (low-priority) should sink down the tree, while one that is too "light" should float or swim up. * The names of the methods in heapq (sift up/down) refer to the motion of the items being compared to, rather than the item being operated on as is usually done in textbooks (i.e. As a result, PQD also supports: - O(1) lookup of an arbitrary element's priority key - O(log n) removal of an arbitrary element - O(log n) updating of an arbitrary element's priority key The standard heap operations used internally are based on those in the python heapq module (here, called "sink" and "swim").* These operations are extended to maintain the internal dictionary. This index is kept up-to-date when the heap is manipulated. The priority queue is implemented as a binary heap, which supports: - O(1) access to the top priority element - O(log n) removal of the top priority element - O(log n) insertion of a new element In addition, an internal dictionary or "index" maps elements to their position in the heap array. A dict-like heap queue to prioritize hashable objects while providing random access and updatable priorities. Inspired by the Python implementation of the heapq module, which was written by Kevin O'Connor and augmented by Tim Peters and Raymond Hettinger. """ """Priority Queue Dictionary - An indexed priority queue data structure. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. Print "%i items in queue" % speech."""Copyright (c) 2012 Nezar Abdennur Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. Respective priority key to get its priority value in the global queue """Add every received data and use its given priority or Self.pq = for priority in range(self.prioritylevels)]ĭef add_to_queue(self, data, priority=None): The constructor builds list for priority queue which would be used later Actually I learned just that probably easier and cleaner way to give the items would be to import chain from functools module, but I did not make the change. Test with 8 priority levels with retrieving values and checking that we do not get lower priority items before higher ones. Here little generalized version allowing to put any data to queue by giving priority as parameter. Changing the level to be hash index of dictionary instead index to list is not big change, also adding priority levels is easy, I added setting those as optional init parameter. In normal list things are un-classified, in this class things go in different 'levels'. ![]() Number of priorities has nothing to do how many elements can be added, it only gives the amount of tiers the things are kept. Looping the queue in reverse order of priority gives these dictionaries: ![]() Print "\nLooping the queue gives these dictionaries:\n"įirstDict = """Add every received dictionary and use its respective priority key to get its priority value in the global queue The constructor contains a PriorityQueue object which would be used later NB: PriorityQueue is a standard python class not a class I built. so I'll paste a part of my original code. Meanwhile, I just tried to write a short python code that shows my problem but the previous code doesn't show it. Thanks for helping me correct my code display.
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