Semi-supervised Non-negative Patch Alignment Framework

Non-negative matrix factorization (NMF) learns the latent semantic space more direct and reliable than the latent semantic indexing (LSI) and the spectral clustering methods, thus performs well in document clustering. Recently, semi-supervised NMF such as N2S2L, CNMF and unsupervised method such as GNMF significantly improve the face recognition performance, but they are designed for classification. In this paper, we combine both geometric structure and label information with NMF under the non-negative patch alignment framework (NPAF) to form SS-NPAF. Due to this combination, it greatly improves the clustering performance. To optimize SS-NPAF, we apply the well-known projected gradient method to overcome the slow convergence problem of the mostly used multiplicative update rule. Experimental results on two popular document datasets, i.e., Reuters21578 and TDT-2, show that SS-NPAF outperforms the representative SS-NMF algorithms.