arXiv:2502.17061stat.MLcs.LG2025-02

揭示随机卷积在时间序列分类中的理论原理,解释其高效与鲁棒性来源。

Random Projections and Natural Sparsity in Time-Series Classification: A Theoretical Analysis

  • 将随机卷积滤波器置于压缩感知框架,证明其能保留关键判别模式。
  • 发现非线性变换本质是利用时间序列固有的稀疏性,提升分类性能。
  • 理论验证其平移不变性和抗噪能力,适合高噪声或数据量大的场景。

时间序列分类在医疗诊断、工业监控、金融预测和人体活动识别等领域至关重要。火箭算法(Rocket)通过在时间序列数据上应用随机卷积核并进行非线性变换,实现了卓越的性能,其架构近似于单隐藏层卷积神经网络,但无需参数训练,具有计算效率优势。尽管其在实践中表现优异,但其理论基础仍不明确。本文通过压缩感知框架形式化分析了火箭的随机卷积滤波器,证明随机投影可保留时间序列中的判别模式。该分析揭示了核参数与信号特征间的关联,为算法配置提供更合理的指导。此外,我们证明其基于卷积后正值比例的非线性变换,本质上反映了时间序列的内在稀疏性。理论还表明,火箭满足平移不变性和抗噪性两个关键条件,增强了模型可解释性,并为极端情况下的参数优化提供依据,推动了时间序列分类的理论与实践发展。

原文摘要 · Abstract (English)

Time-series classification is essential across diverse domains, including medical diagnosis, industrial monitoring, financial forecasting, and human activity recognition. The Rocket algorithm has emerged as a simple yet powerful method, achieving state-of-the-art performance through random convolutional kernels applied to time-series data, followed by non-linear transformation. Its architecture approximates a one-hidden-layer convolutional neural network while eliminating parameter training, ensuring computational efficiency. Despite its empirical success, fundamental questions about its theoretical foundations remain unexplored. We bridge theory and practice by formalizing Rocket's random convolutional filters within the compressed sensing framework, proving that random projections preserve discriminative patterns in time-series data. This analysis reveals relationships between kernel parameters and input signal characteristics, enabling more principled approaches to algorithm configuration. Moreover, we demonstrate that its non-linearity, based on the proportion of positive values after convolutions, expresses the inherent sparsity of time-series data. Our theoretical investigation also proves that Rocket satisfies two critical conditions: translation invariance and noise robustness. These findings enhance interpretability and provide guidance for parameter optimization in extreme cases, advancing both theoretical understanding and practical application of time-series classification.

时间序列随机投影压缩感知分类

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