How can I implement decrease-key functionality in Python's heapq?

Question

I know it is possible to realize decrease-key functionality in O(log n) but I don\'t know how?

Answer 1

The heapq documentation has an entry on exactly how to do this.

However, I have written a heap package that does exactly this (it is a wrapper around heapq). So if you have pip or easy_install you could do something like

pip install heap

Then in your code write

from heap.heap import heap

h = heap()

h['hello'] = 4 # Insert item with priority 4.

h['hello'] = 2 # Update priority/decrease-key has same syntax as insert. 

It is pretty new though, so might be full of bugs.