There were bugs in my earlier code, but now the intended meaning of %union_data is actually fulfilled.

Given two numeric keys for vertices in a graph, the UnionFind "union" operation creates an edge joining them and returns one of the two keys as a master key to the joined vertex set. What I am doing with %union_data is supplementing the algorithm -- under each master key, there is a bit-vector with the union of all bits that are true in any member of the joined set.

In my implementation, the vertices are item numbers, so the key to %union_data is a subset of the item numbers. The binary values are bit vectors: bit [k] is true if keyword[k] is in the set.

This allows me to extend the partition easily by testing each new item against the joined sets that have already been built.

In reply to Re^4: algorithm for 'best subsets' by tall_man
in thread algorithm for 'best subsets' by halley

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