Cluster Ensembles --- A Knowledge Reuse Framework for Combining Multiple Partitions
Alexander Strehl, Joydeep Ghosh;
3(Dec):583-617, 2002.
Abstract
This paper introduces the problem of combining multiple partitionings
of a set of objects into a single consolidated clustering
without accessing the features or algorithms that determined these
partitionings. We first identify several application scenarios for
the resultant 'knowledge reuse' framework that we call
cluster ensembles.
The cluster ensemble problem is then formalized as a combinatorial
optimization problem in terms of shared mutual information. In
addition to a direct maximization approach, we propose three effective
and efficient techniques for obtaining high-quality combiners
(consensus functions). The first combiner induces a similarity
measure from the partitionings and then reclusters the objects. The
second combiner is based on hypergraph partitioning. The third one
collapses groups of clusters into meta-clusters which then compete for
each object to determine the combined clustering. Due to the low
computational costs of our techniques, it is quite feasible to use a
supra-consensus function that evaluates all three approaches against
the objective function and picks the best solution for a given
situation.
We evaluate the effectiveness of cluster ensembles in three
qualitatively different application scenarios: (i) where the original
clusters were formed based on non-identical sets of features, (ii)
where the original clustering algorithms worked on non-identical sets
of objects, and (iii) where a common data-set is used and the main
purpose of combining multiple clusterings is to improve the quality and
robustness of the solution. Promising results are obtained in all
three situations for synthetic as well as real data-sets.
[abs]
[pdf]
[ps.gz]
[ps]
