Clustering: Algorithms and Applications

In this paper, we describe algorithms that perform fuzzy clustering and feature weighting simultaneously and in an unsupervised manner. These algorithms are conceptually and computationally simple, and learn a different set of feature weights for each identified cluster. The cluster dependent feature weights offer two advantages. First, they guide the clustering process to partition the data into more meaningful clusters. Second, they can be used in the subsequent steps of a learning system to improve its learning behavior. An extension of the algorithm to deal with an unknown number of clusters is also presented. The extension is based on competitive agglomeration, whereby the number of clusters is over-specified, and adjacent clusters are allowed to compete for data points in a manner that causes clusters which lose in the competition to gradually become depleted and vanish. We illustrate the performance of the proposed approach by using it to segment color images, categorize text document collections, and build a multi-modal thesaurus and use it to annotate image regions.