Nearest Neighbors in Random Subspaces

Recent studies have shown that the random subspace method can be used to create multiple independent tree-classifiers that can be combined to improve accuracy. We apply the procedure to k-nearest-neighbor classifiers and show that it can achieve similar results. We examine the effects of several parameters of the method by experiments using data from a digit recognition problem. We show that the combined accuracies follow a trend of increase with increasing number of component classifiers, and that with an appropriate subspace dimensionality, the method can be superior to simple k-nearest-neighbor classification, The method's superiority is maintained when smaller number of training prototypes are available, i.e., when conventional knn classifiers suffer most heavily from the curse of dimensionality.