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计算机工程 ›› 2024, Vol. 50 ›› Issue (6): 110-123. doi: 10.19678/j.issn.1000-3428.0068354

• 人工智能与模式识别 • 上一篇    下一篇

基于持续同调的倾斜时间序列分类算法

严银凯, 彭宁宁, 易丽莎   

  1. 武汉理工大学理学院, 湖北 武汉 430070
  • 收稿日期:2023-09-07 修回日期:2023-11-27 发布日期:2024-03-19
  • 通讯作者: 彭宁宁,E-mail:pengn@whut.edu.cn E-mail:pengn@whut.edu.cn
  • 基金资助:
    国家自然科学基金(11701438)。

Skewed Time Series Classification Algorithm Based on Persistent Homology

YAN Yinkai, PENG Ningning, YI Lisha   

  1. School of Science, Wuhan University of Technology, Wuhan 430070, Hubei, China
  • Received:2023-09-07 Revised:2023-11-27 Published:2024-03-19

摘要: 针对现有时间序列分类算法对高维拓扑信息以及时序顺序信息提取能力不足等问题,提出一种基于持续同调的倾斜时间序列分类算法。该算法结合时序数据方差,将原始单变量时序数据嵌入二维点云,同时展现出周期内和周期间的时序变化;在滑动窗口划分的子区间上进行时间倾斜,将点云分解为不同结构,从而使算法适应更多的时序数据,有效捕捉时序顺序信息;利用持续同调技术在点云上构建Vietoris-Rips(VR)复形流,从不同尺度分析各个维度下孔洞数量的变化,从而提取到更全面的时序数据的拓扑结构特征,并通过计算持久性图像得到点云中的拓扑特征。在此基础上,以持久性中心表示向量作为输入,使用随机森林模型对点云进行分类。在9个UCR时间序列数据集上进行对比实验,结果显示,该算法在其中8个数据集上取得了最高的准确率,相较于其他6种传统时间序列分类算法分类准确率提高了0.5~24个百分点,F1值提高了0.9~23.9个百分点,表明该算法在时间序列数据分类方面具有较高的精度和良好的鲁棒性。

关键词: 时间序列, 时间序列分类, 时间倾斜, 持续同调, 持久性图

Abstract: To address the limitations of traditional time series classification algorithms to extract high-dimensional topological information and temporal sequence information, this paper proposes a skewed time series classification algorithm based on persistent homology for extracting high-dimensional topological and temporal sequential information. The algorithm combines the variance of temporal data to embed univariate time series data into a two-dimensional point cloud, displaying temporal changes within and between cycles. It performs a time skew on the subintervals divided by the sliding window and decomposes the point cloud into different structures through time skew. Thus, the algorithm can adapt to more temporal data and effectively capture temporal order information. It uses persistent homology technology to construct Vietoris-Rips(VR) complex flows on point clouds, analyzes the changes in number of holes in various dimensions at different scales to extract more comprehensive topological structural features of the temporal data, and obtains topological features in point clouds by calculating persistence diagram. It uses persistent center representation vectors as input and classifies point clouds using a random forest model. The results of comparative experiments performed on nine UCR time series datasets show that the algorithm achieves the highest accuracy on eight of these datasets. Compared to six traditional time series classification algorithms, the algorithm achieves classification accuracy improvement and increase in F1 value by 0.5-24 percentage points and 0.9-23.9 percentage points, respectively. This indicates its higher accuracy and good robustness in time series data classification.

Key words: time series, time series classification, time skew, persistent homology, persistence diagram

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