A Hidden Feature Selection Method based on l2,0-Norm Regularization for Training Single-hidden-layer Neural Networks

Feature selection is an important data preprocessing for machine learning. It can improve the performance of machine learning algorithms by removing redundant and noisy features. Among all the methods, those based on l1-norms or l2,1-norms have received considerable attention due to their good performance. However, these methods cannot produce exact row sparsity to the weight matrix, so the number of selected features cannot be determined automatically without using a threshold. To this end, this paper proposes a feature selection method incorporating the l2,0-norm, which can guarantee exact row sparsity of weight matrix. A method based on iterative hard thresholding (IHT) algorithm is also proposed to solve the l2,0- norm regularized least square problem. For fully using the role of row-sparsity induced by the l2,0-norm, this method acts as network pruning for single-hidden-layer neural networks. This method is conducted on the hidden features and it can achieve node-level pruning rather than the connection-level pruning. The experimental results in several public data sets and three image recognition data sets have shown that this method can not only effectively prune the useless hidden nodes, but also obtain better performance.