Pruned Random Subspace Method for One-Class Classifiers

The goal of one-class classification is to distinguish the target class from all the other classes using only training data from the target class. Because it is difficult for a single one-class classifier to capture all the characteristics of the target class, combining several one-class classifiers may be required. Previous research has shown that the Random Subspace Method (RSM), in which classifiers are trained on different subsets of the feature space, can be effective for one-class classifiers. In this paper we show that the performance by the RSM can be noisy, and that pruning inaccurate classifiers from the ensemble can be more effective than using all available classifiers. We propose to apply pruning to RSM of one-class classifiers using a supervised AUC criterion or an unsupervised consistency criterion. It appears that when the AUC criterion is used, the performance may be increased dramatically, while for the consistency criterion results do not improve, but only become more predictable.