The effectiveness of lloyd-type methods for the k-means problem

  • Authors:
  • Rafail Ostrovsky;Yuval Rabani;Leonard J. Schulman;Chaitanya Swamy

  • Affiliations:
  • University of California, Los Angeles, CA;The Hebrew University of Jerusalem, Jerusalem, Israel;California Institute of Technology, Pasadena, CA;University of Waterloo, Waterloo, Canada

  • Venue:
  • Journal of the ACM (JACM)
  • Year:
  • 2013

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Abstract

We investigate variants of Lloyd's heuristic for clustering high-dimensional data in an attempt to explain its popularity (a half century after its introduction) among practitioners, and in order to suggest improvements in its application. We propose and justify a clusterability criterion for data sets. We present variants of Lloyd's heuristic that quickly lead to provably near-optimal clustering solutions when applied to well-clusterable instances. This is the first performance guarantee for a variant of Lloyd's heuristic. The provision of a guarantee on output quality does not come at the expense of speed: some of our algorithms are candidates for being faster in practice than currently used variants of Lloyd's method. In addition, our other algorithms are faster on well-clusterable instances than recently proposed approximation algorithms, while maintaining similar guarantees on clustering quality. Our main algorithmic contribution is a novel probabilistic seeding process for the starting configuration of a Lloyd-type iteration.