Pseudo Oversampling Based on Feature Transformation and Fuzzy Membership Functions for Imbalanced and Overlapping Data

Abstract

Class imbalance in data poses challenges for classifier learning, drawing increased attention in data mining and machine learning. The occurrence of class overlap in real-world data exacerbates the learning difficulty. In this paper, a novel pseudo oversampling method (POM) is proposed to learn imbalanced and overlapping data. It is motivated by the point that overlapping samples from different classes share the same distribution space, and therefore information underlying in majority (negative) overlapping samples can be extracted and used to generate additional positive samples. A fuzzy logic-based membership function is defined to assess negative overlaps using both local and global information. Subsequently, the identified negative overlapping samples are shifted into the positive sample region by a transformation matrix, centered around the positive samples. POM outperforms 15 methods across 14 datasets, displaying superior performance in terms of metrics of <i>G<sub>m</sub></i>, <I>F</I><sub>1</sub> and <I>AUC</I>.