RBTree.py -- Red/Black Balanced Binary Trees with Dictionary Interface

Introduction:

This code adapted from C source from
Thomas Niemann's Sorting and Searching Algorithms: A Cookbook

From the title page:
    Permission to reproduce this document, in whole or in part, is 
    given provided the original web site listed below is referenced, 
    and no additional restrictions apply. Source code, when part of 
    a software project, may be used freely without reference to the 
    author.

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Usage:

RBTree.py defines a class, RBDict, which creates dictionary-like objects
implemented using a Red/Black tree (a form of balanced binary tree). 

Red/Black trees, I'm told, remain "nearly" balanced, and evidently the
algorithm is somehow inferior to the AVL tree.  However, Red/Black trees
have similar performance and the algorithm is much simpler IMHO.

Anyway, an RBDict instance behaves in almost every way like a dictionary;
however the .keys() method returns ordered keys instead of the "random"
keys returned by the normal (hashed) dictionary.

RBTree.py also contains a class, RBTree, which defines the tree without
the dictionary interface; RBDict is a subclass of RBTree, adding the 
interface goodies.

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Installation:

RBTree.py contains an internal Distutils-based installer; just run:

    python RBTree.py install

(as root/Administrator if needed) and you're done.

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