Distance metric learning revisited

  • Authors:
  • Qiong Cao;Yiming Ying;Peng Li

  • Affiliations:
  • College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK;College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK;Department of Engineering Mathematics, University of Bristol, Bristol, UK

  • Venue:
  • ECML PKDD'12 Proceedings of the 2012 European conference on Machine Learning and Knowledge Discovery in Databases - Volume Part I
  • Year:
  • 2012

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Abstract

The success of many machine learning algorithms (e.g. the nearest neighborhood classification and k-means clustering) depends on the representation of the data as elements in a metric space. Learning an appropriate distance metric from data is usually superior to the default Euclidean distance. In this paper, we revisit the original model proposed by Xing et al. [25] and propose a general formulation of learning a Mahalanobis distance from data. We prove that this novel formulation is equivalent to a convex optimization problem over the spectrahedron. Then, a gradient-based optimization algorithm is proposed to obtain the optimal solution which only needs the computation of the largest eigenvalue of a matrix per iteration. Finally, experiments on various UCI datasets and a benchmark face verification dataset called Labeled Faces in the Wild (LFW) demonstrate that the proposed method compares competitively to those state-of-the-art methods.