Balanced trees (was: Re: Tuples and immutability)

Dan Stromberg drsalists at
Sat Mar 8 20:58:25 CET 2014

On Sat, Mar 8, 2014 at 12:34 AM, Marko Rauhamaa <marko at> wrote:
> Ian Kelly <ian.g.kelly at>:
>> I already mentioned this earlier in the thread, but a balanced binary
>> tree might implement += as node insertion and then return a different
>> object if the balancing causes the root node to change.
> True.
> Speaking of which, are there plans to add a balanced tree to the
> "batteries" of Python? Timers, cache aging and the like need it. I'm
> using my own AVL tree implementation, but I'm wondering why Python
> still doesn't have one.

I think it'd probably be a good idea to add one or more balanced
binary trees to the standard library.  But I suspect it's been tried
before, and didn't happen.  It might be good to add an _un_balanced
tree too, since they do quite well with random keys.

Here's a performance comparison I did of a bunch of tree types in Python:

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