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

Decrease-key is a must-have operation for many algorithms (Dijkstra's Algorithm, A*, OPTICS), i wonder why Python's built-in priority queue does not support it.

Unfortunately, i wasn't able to download math4tots's package.

But, i was able to find this implementation by Daniel Stutzbach. Worked perfectly for me with Python 3.5.

hd = heapdict()
hd[obj1] = priority
hd[obj1] = lower_priority
# ...
obj = hd.pop()