A flexible priority queue library with support for pluggable storage strategies and fast lookups and mutability.
PriorityQ is a library for managing a priority queue (PQ) with a cleaner API to enable custom comparators, finding references to values efficiently (in constant time) and deleting values from the PQ. This was developed because the current heapq module (in python’s standard library) does not provide an efficient find operation (it is O(n)) and has no easy way to deleting an element and ensuring the heap invariant afterwards.
- O(1) finding of elements
- Deletion of elements possible (in O(log n)).
- Adjusting of the priority of an element without requiring a deletion followed by an insertion.
- Opaque handles to elements that can be used to reference to the same item again.
- Duplicate elements allowed.
- Custom comparator function can be passed to the PQ itself instead of needing to implement __cmp__.
It is simple to use
To create a PQ simply do:
# A simple object with a comparator class Item(object): def __init__(self, value): self.value = value def __cmp__(self, another): return cmp(self.value, another.value) from priorityq import PQ pq = PQ() pq.heapify([Item(r) for r in [1, 10, 2, 20, 4, 7, 9, 3, 5, 6]]) print list(pq) # Should print: # 1 2 3 4 5 6 7 9 10 20 handle_10 = pq.find(10) # Happens in O(1) handle_10.value = 25 # Modify its value - O(log n) pq.adjust(handle_10) # Indicate to the heap to reprioritise/adjust it print list(pq) # Should print: # 1 2 3 4 5 6 7 9 20 25 handle_10.value = 10 # Modify its value using the same opaque handle as before pq.adjust(handle_10) # Indicate to the heap to reprioritise/adjust it print list(pq) # Should print: # 1 2 3 4 5 6 7 9 10 20
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
|Filename, size & hash SHA256 hash help||File type||Python version||Upload date|
|priorityq-0.0.9-py2.py3-none-any.whl (21.5 kB) Copy SHA256 hash SHA256||Wheel||py2.py3||Mar 2, 2017|
|priorityq-0.0.9.tar.gz (10.7 kB) Copy SHA256 hash SHA256||Source||None||Mar 2, 2017|