Instance Selection and Outlier Generation to Improve the Cascade Classifier Precision

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• 关键词：Time series classification ; High ; dimensional classification ; Imbalanced learning ; Data preprocessing
• 刊名：Lecture Notes in Computer Science
• 出版年：2017
• 出版时间：2017
• 年：2017
• 卷：10162
• 期：1
• 页码：151-170
• 丛书名：Agents and Artificial Intelligence
• ISBN：978-3-319-53354-4
• 卷排序：10162

文摘

Classification of high-dimensional time series with imbalanced classes is a challenging task. For such classification tasks, the cascade classifier has been proposed. The cascade classifier tackles high-dimensionality and imbalance by splitting the classification task into several low-dimensional classification tasks and aggregating the intermediate results. Therefore the high-dimensional data set is projected onto low-dimensional subsets. But these subsets can employ unfavorable and not representative data distributions, that hamper classifiction again. Data preprocessing can overcome these problems. Small improvements in the low-dimensional data subsets of the cascade classifier lead to an improvement of the aggregated overall results. We present two data preprocessing methods, instance selection and outlier generation. Both methods are based on point distances in low-dimensional space. The instance selection method selects representative feasible examples and the outlier generation method generates artificial infeasible examples near the class boundary. In an experimental study, we analyse the precision improvement of the cascade classifier due to the presented data preprocessing methods for power production time series of a micro Combined Heat and Power plant and an artificial and complex data set. The precision increase is due to an increased selectivity of the learned decision boundaries. This paper is an extended version of [19], where we have proposed the two data preprocessing methods. In this paper we extend the analysis of both algorithms by a parameter sensitivity analysis of the distance parameters from the preprocessing methods. Both distance parameters depend on each other and have to be chosen carefully. We study the influence of these distance parameters on the classification precision of the cascade model and derive parameter fitting rules for the \(\mu \)CHP data set. The experiments yield a region of optimal parameter value combinations leading to a high classification precision.