Tree-based mining contrast subspace

All existing mining contrast subspace methods employ density-based likelihood contrast scoring function to measure the likelihood of a query object to a target class against other class in a subspace. However, the density tends to decrease when the dimensionality of subspaces increases causes its bounds to identify inaccurate contrast subspaces for the given query object. This paper proposes a novel contrast subspace mining method that employs tree-based likelihood contrast scoring function which is not affected by the dimensionality of subspaces. The tree-based scoring measure recursively binary partitions the subspace space in the way that objects belong to the target class are grouped together and separated from objects belonging to other class. In contrast subspace, the query object should be in a group having a higher number of objects of the target class than other class. It incorporates the feature selection approach to find a subset of one-dimensional subspaces with high likelihood contrast score with respect to the query object. Therefore, the contrast subspaces are then searched through the selected subset of one-dimensional subspaces. An experiment is conducted to evaluate the effectiveness of the tree-based method in terms of classification accuracy. The experiment results show that the proposed method has higher classification accuracy and outperform the existing method on several real-world data sets

Fast, explainable view detection to characterize exploration queries

The aim of data exploration is to get acquainted with an unfamiliar database. Typically, explorers operate by trial and error: they submit a query, study the result, and refine their query subsequently. In this paper, we investigate how to help them understand their query results. In particular, we focus on medium to high dimension spaces: if the database contains dozens or hundreds of columns, which variables should they inspect? We propose to detect subspaces in which the users' selection is different from the rest of the database. From this idea, we built Ziggy, a tuple description engine. Ziggy can detect informative subspaces, and it can explain why it recommends them, with visualizations and natural language. It can cope with mixed data, missing values, and it penalizes redundancy. Our experiments reveal that it is up to an order of magnitude faster than state-of-the-art feature selection algorithms, at minimal accuracy costs