Selection of Import Vectors via Binary Particle Swarm Optimization and Cross-Validation for Kernel Logistic Regression

Kernel logistic regression (KLR) is a powerful discriminative algorithm. It has similar loss function and algorithmic structure to the kernel support vector machine (SVM). Recently, Zhu and Hastie proposed the import vector machine (IVM) in which a subset of the input vectors of KLR are selected by minimizing the regularized negative log-likelihood to improve the generalization performance and to reduce computation cost. In this paper, two modifications of the original IVM are proposed. The cross-validation based criterion is used to select import vectors instead of the likelihood based criterion. Also binary particle swarm optimization is used to select good subset instead of the greedy stepwise algorithm of the original IVM. Through the comparison experiment, the improvement of the generalization performance of the proposed algorithm was confirmed.