Low Rank Metric Learning with Manifold Regularization

In this paper, we present a semi-supervised method to learn a low rank Mahalanobis distance function. Based on an approximation to the projection distance from a manifold, we propose a novel parametric manifold regularizer. In contrast to previous approaches that usually exploit side information only, our proposed method can further take advantages of the intrinsic manifold information from data. In addition, we focus on learning a metric of low rank directly, this is different from traditional approaches that often enforce the l_1 norm on the metric. The resulting configuration is convex with respect to the manifold structure and the distance function, respectively. We solve it with an alternating optimization algorithm, which proves effective to find a satisfactory solution. For efficient implementation, we even present a fast algorithm, in which the manifold structure and the distance function are learned independently without alternating minimization. Experimental results over 12 standard UCI data sets demonstrate the advantages of our method.