Skip to main content

Heap Implementation for Python

Project description

It’s like heapq (blazingly fast) but object-oriented + more features.

Read more here for the background story.


Less code.

What are heaps good for anyway?

When you need the smallest item of a large list—fast and with no overhead.


Let’s suppose you have a heap, you can use pop to get its smallest item.

from xheap import Heap

heap = Heap(['H', 'D', 'B', 'A', 'E', 'C', 'L', 'J', 'I'])
heap.pop()   # returns A
heap.pop()   # returns B
heap.pop()   # returns C
heap.pop()   # returns D

Heapsort works this way.

Can I insert an item?

Indeed and it’s as fast as pop. Use push for insertion.

heap = Heap(['A', 'D', 'B', 'H', 'E', 'C', 'L', 'J', 'I'])

Can I remove an item from the middle of a heap?

Yes, that’s what RemovalHeap.remove is supposed to do.

from xheap import RemovalHeap

heap = RemovalHeap(['A', 'D', 'B', 'H', 'E', 'C', 'L', 'J', 'I'])

Can I specify the order of the heap?

Just imagine two heaps of the very same set of items but you need different sorting for each heap. Or you need a max-heap instead of a min-heap. That is what OrderHeap is designed for:

from xheap import OrderHeap

items = [date(2016, 1, 1), date(2016, 1, 2),  date(2016, 1, 3),  date(2016, 1, 4)]

day_heap = OrderHeap(items, key=lambda date:
day_heap.peek()      # returns date(2016, 1, 1)

weekday_heap = OrderHeap(items, key=lambda date: date.weekday())
weekday_heap.peek()  # returns date(2016, 1, 4)

What about both remove+order?

No problem. Use XHeap.

If you wonder why there are 4 distinct heap implementations, it’s a matter of speed. Each additional feature slows a heap down. Thus, you could always use XHeap but beware of the slowdown.

Checking Heap Invariant

A heap is just a list. So, if you tinker with it, you can check whether its invariant still holds:

heap = Heap([4, 3, 7, 6, 1, 2, 9, 8, 5])
heap[3] = 10           # I know what I am doing here
heap.check_invariant() # but better check... ooops



  • uses C implementation if available (i.e. fast)
  • object-oriented
  • no slowdown if you don’t need more than a simple heap
  • removal possible
  • custom orders possible
  • works with Python2 and Python3


  • no drawbacks discovered so far ;-)
  • needs fix/work:
    • item wrapper which allows duplicate items
    • decrease-key+increase-key: another missing use-case of heapq
    • merge heaps
  • ideas are welcome :-)

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for xheap, version 0.17
Filename, size File type Python version Upload date Hashes
Filename, size xheap-0.17-py2.py3-none-any.whl (3.7 kB) File type Wheel Python version py2.py3 Upload date Hashes View
Filename, size xheap-0.17.tar.gz (4.5 kB) File type Source Python version None Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page