Jesus Cea said:

> Current durus btree implementation is indexed by key. So you can
> get the
> smaller or the bigger key in the btree, or iterate the btree, just
> fine.
>
> For an application I'm designing just now, I would need a "counted"
> btree, just like explained in
> http://www.chiark.greenend.org.uk/~sgtatham/algorithms/cbtree.html
>
> This structure can retrieve the i-th element in the btree very easily,
> without knowing its key. Also, "len()" would be very fast.

I just stumbled across this same need and option.

Did you ever implement this?

Dave