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In many machine learning applications such as computer-aided diagnosis, gene sequence analysis or natural language processing, categorical data appears. For small-scale data set with high dimensions, since relatively small proportion of possible categorical configurations are covered by training samples, conventional methods based on frequency information such as Dirichlet Compound Multinomial distribution usually runs into problems of over-fitting. Latent gaussian process is an effective bayesian non-parametric technique for categorical data modeling, which was proposed as an unsupervised method to embed unlabelled categorical data into a continuous and low-dimensional space through gaussian process. As a probabilistic generative model, latent gaussian process owns the ability of density estimation. In this paper, we propose a generative classification model as a supervised method for labelled categorical data, in which we use latent gaussian process to estimate the class-conditional densities. Since the complexity of gaussian process model can adapt to the size of training data, our method is able to effectively model small-sale categorical data. Experimental results show that our proposal can achieve better classification performance compared with other classification models for categorical data. [ABSTRACT FROM AUTHOR]

Traditional Data Field Hierarchical Clustering Algorithm (DFHCA) uses brute force method to compute the forces exert on each object. The computation complexity increases as O ( n 2 ). In this study, we improve the force computation efficiency of DFHCA to O ( n log  n ). We use the Barnes–Hut tree to reduce the number of force computation by approximating far away particles with their center of mass. And compared with traditional method, our method does not need to tune the parameters. In our implementation, we discuss two different merging strategies. Experimental results show that the proposed method could improve the computation efficiency under the same settings. We also find that DFHCA-M merging strategy converges faster than DFHCA-S merging strategy. Finally, we compare and analyze the time complexity and space complexity of our algorithm. [ABSTRACT FROM AUTHOR]