新方法突破传统异常检测局限,精准识别复杂多模态数据中的异常点。
Localized Kernel Projection Outlyingness: A Two-Stage Approach for Multi-Modal Outlier Detection
- 先用核PCA线性化非线性结构,再局部聚类捕捉多峰分布
- 在10个基准数据集上表现最优,尤其在多簇和高维数据上大幅领先
- 适合处理结构复杂、多模态的异常检测任务,可作为通用工具
本文提出Two-Stage LKPLO,一种新型多阶段异常检测框架,克服了传统投影方法依赖固定统计度量、假设单一数据结构的缺陷。该框架融合三项核心思想:(1) 采用广义损失函数定义异常度(PLO),以SVM类似损失实现灵活自适应;(2) 通过全局核PCA阶段线性化非线性数据结构;(3) 后续局部聚类阶段处理多模态分布。在10个基准数据集上进行5折交叉验证,配合自动超参数优化,结果表明Two-Stage LKPLO达到当前最优性能,尤其在多簇数据(Optdigits)与高维复杂数据(Arrhythmia)中显著优于强基线方法。消融实验证实核化与局部化阶段的协同作用不可或缺。本工作为一类重要异常检测问题提供了强大工具,并强调混合多阶段架构的价值。
原文摘要 · Abstract (English)
This paper presents Two-Stage LKPLO, a novel multi-stage outlier detection framework that overcomes the coexisting limitations of conventional projection-based methods: their reliance on a fixed statistical metric and their assumption of a single data structure. Our framework uniquely synthesizes three key concepts: (1) a generalized loss-based outlyingness measure (PLO) that replaces the fixed metric with flexible, adaptive loss functions like our proposed SVM-like loss; (2) a global kernel PCA stage to linearize non-linear data structures; and (3) a subsequent local clustering stage to handle multi-modal distributions. Comprehensive 5-fold cross-validation experiments on 10 benchmark datasets, with automated hyperparameter optimization, demonstrate that Two-Stage LKPLO achieves state-of-the-art performance. It significantly outperforms strong baselines on datasets with challenging structures where existing methods fail, most notably on multi-cluster data (Optdigits) and complex, high-dimensional data (Arrhythmia). Furthermore, an ablation study empirically confirms that the synergistic combination of both the kernelization and localization stages is indispensable for its superior performance. This work contributes a powerful new tool for a significant class of outlier detection problems and underscores the importance of hybrid, multi-stage architectures.
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