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Iterative hard thresholding (IHT) is a projected gradient descent algorithm, known to achieve state of the art performance for a wide range of structured estimation problems, such as sparse inference. In this work, we consider IHT as a…

Machine Learning · Statistics 2020-02-03 Jacky Y. Zhang , Rajiv Khanna , Anastasios Kyrillidis , Oluwasanmi Koyejo

The forecasting of irregular multivariate time series (IMTS) is crucial in key areas such as healthcare, biomechanics, climate science, and astronomy. However, achieving accurate and practical predictions is challenging due to two main…

Machine Learning · Computer Science 2025-11-18 Xvyuan Liu , Xiangfei Qiu , Xingjian Wu , Zhengyu Li , Chenjuan Guo , Jilin Hu , Bin Yang

We develop a novel algorithm for feature extraction in time series data by leveraging tools from topological data analysis. Our algorithm provides a simple, efficient way to successfully harness topological features of the attractor of the…

Computational Geometry · Computer Science 2019-06-05 Kwangho Kim , Jisu Kim , Alessandro Rinaldo

Traffic forecasting is a critical service in Intelligent Transportation Systems (ITS). Utilizing deep models to tackle this task relies heavily on data from traffic sensors or vehicle devices, while some cities might lack device support and…

Machine Learning · Computer Science 2023-08-22 Zhanyu Liu , Guanjie Zheng , Yanwei Yu

Matrix factorisation methods decompose multivariate observations as linear combinations of latent feature vectors. The Indian Buffet Process (IBP) provides a way to model the number of latent features required for a good approximation in…

Machine Learning · Statistics 2017-04-14 Matthew C. Pearce , Simon R. White

Estimation of a sparse spectral precision matrix, the inverse of a spectral density matrix, is a canonical problem in frequency-domain analysis of high-dimensional time series (HDTS), with applications in neurosciences and environmental…

Methodology · Statistics 2025-11-11 Navonil Deb , Amy Kuceyeski , Sumanta Basu

Feature selection is an important tool to deal with high dimensional data. In unsupervised case, many popular algorithms aim at maintaining the structure of the original data. In this paper, we propose a simple and effective feature…

Machine Learning · Statistics 2020-04-06 Xiaoyun Li , Chengxi Wu , Ping Li

In this paper, we focus our attention on the high-dimensional double sparse linear regression, that is, a combination of element-wise and group-wise sparsity. To address this problem, we propose an IHT-style (iterative hard thresholding)…

Statistics Theory · Mathematics 2024-12-10 Yanhang Zhang , Zhifan Li , Shixiang Liu , Jianxin Yin

The problems of uniform linear array (with uniform mutual coupling) calibration and Toeplitz covariance matrix estimation are re-examined for application in the receive arrays of modern High Frequency Over-the-Horizon Radars (HF OTHR).…

Signal Processing · Electrical Eng. & Systems 2024-09-20 Yuri Abramovich , Tanit Pongsiri

This paper focuses on detection tasks in information extraction, where positive instances are sparsely distributed and models are usually evaluated using F-measure on positive classes. These characteristics often result in deficient…

Computation and Language · Computer Science 2018-05-29 Hongyu Lin , Yaojie Lu , Xianpei Han , Le Sun

Irregular Multivariate Time Series (IMTS) are characterized by uneven intervals between consecutive timestamps, which carry sampling pattern information valuable and informative for learning temporal and variable dependencies. In addition,…

Machine Learning · Computer Science 2026-02-26 Boyuan Li , Zhen Liu , Yicheng Luo , Qianli Ma

Real-world time series typically exhibit complex temporal variations, making the time series classification task notably challenging. Recent advancements have demonstrated the potential of multi-scale analysis approaches, which provide an…

Artificial Intelligence · Computer Science 2025-07-25 Zhipeng Liu , Peibo Duan , Binwu Wang , Xuan Tang , Qi Chu , Changsheng Zhang , Yongsheng Huang , Bin Zhang

Most current multivariate time series (MTS) classification algorithms focus on improving the predictive accuracy. However, for large-scale (either high-dimensional or long-sequential) time series (TS) datasets, there is an additional…

Machine Learning · Computer Science 2022-03-29 Yuqing Wang , Yun Zhao , Linda Petzold

This paper addresses the problem of estimating the Hermitian Toeplitz covariance matrix under practical hardware constraints of sparse observations and coarse quantization. Within the triangular-dithered quantization framework, we propose…

Signal Processing · Electrical Eng. & Systems 2025-12-30 Hongwei Xu , Weichao Zheng , Zai Yang

Feature selection identifies subsets of informative features and reduces dimensions in the original feature space, helping provide insights into data generation or a variety of domain problems. Existing methods mainly depend on feature…

Machine Learning · Computer Science 2021-06-07 Xinxing Wu , Qiang Cheng

We propose a method to reconstruct and cluster incomplete high-dimensional data lying in a union of low-dimensional subspaces. Exploring the sparse representation model, we jointly estimate the missing data while imposing the intrinsic…

Computer Vision and Pattern Recognition · Computer Science 2017-09-06 João Carvalho , Manuel Marques , João P. Costeira

In this paper, we describe a new algorithm to build a few sparse principal components from a given data matrix. Our approach does not explicitly create the covariance matrix of the data and can be viewed as an extension of the Kogbetliantz…

Machine Learning · Computer Science 2022-02-09 Cristian Rusu

Irregularly-sampled time series (ITS) are native to high-impact domains like healthcare, where measurements are collected over time at uneven intervals. However, for many classification problems, only small portions of long time series are…

Machine Learning · Computer Science 2023-02-09 Thomas Hartvigsen , Jidapa Thadajarassiri , Xiangnan Kong , Elke Rundensteiner

In time series analysis, when fitting an autoregressive model, one must solve a Toeplitz ordinary least squares problem numerous times to find an appropriate model, which can severely affect computational times with large data sets. Two…

Machine Learning · Statistics 2021-12-28 Ali Eshragh , Oliver Di Pietro , Michael A. Saunders

Importance sampling (IS) as an elegant and efficient variance reduction (VR) technique for the acceleration of stochastic optimization problems has attracted many researches recently. Unlike commonly adopted stochastic uniform sampling in…

Machine Learning · Computer Science 2017-11-02 Fei Wang , Xiaofeng Gao , Guihai Chen , Jun Ye