Search Results for author: Francois Petitjean

Found 16 papers, 12 papers with code

Elastic Similarity and Distance Measures for Multivariate Time Series

1 code implementation20 Feb 2021 Ahmed Shifaz, Charlotte Pelletier, Francois Petitjean, Geoffrey I. Webb

Elastic similarity and distance measures are a class of similarity measures that can compensate for misalignments in the time axis of time series data.

Classification Dynamic Time Warping +5

Tight lower bounds for Dynamic Time Warping

1 code implementation14 Feb 2021 Geoffrey I. Webb, Francois Petitjean

Due to DTW's high computation time, lower bounds are often employed to screen poor matches.

Computational Efficiency Dynamic Time Warping +2

Discriminative, Generative and Self-Supervised Approaches for Target-Agnostic Learning

no code implementations12 Nov 2020 Yuan Jin, Wray Buntine, Francois Petitjean, Geoffrey I. Webb

For this task, we survey a wide range of techniques available for handling missing values, self-supervised training and pseudo-likelihood training, and adapt them to a suite of algorithms that are suitable for the task.

Self-Supervised Learning

Seasonal Averaged One-Dependence Estimators: A Novel Algorithm to Address Seasonal Concept Drift in High-Dimensional Stream Classification

1 code implementation27 Jun 2020 Rakshitha Godahewa, Trevor Yann, Christoph Bergmeir, Francois Petitjean

This paper explores how to best handle seasonal drift in the specific context of news article categorization (or classification/tagging), where seasonal drift is overwhelmingly the main type of drift present in the data, and for which the data are high-dimensional.

Classification General Classification

Time Series Extrinsic Regression

1 code implementation23 Jun 2020 Chang Wei Tan, Christoph Bergmeir, Francois Petitjean, Geoffrey I. Webb

This paper studies Time Series Extrinsic Regression (TSER): a regression task of which the aim is to learn the relationship between a time series and a continuous scalar variable; a task closely related to time series classification (TSC), which aims to learn the relationship between a time series and a categorical class label.

regression Time Series +3

Monash University, UEA, UCR Time Series Extrinsic Regression Archive

2 code implementations19 Jun 2020 Chang Wei Tan, Christoph Bergmeir, Francois Petitjean, Geoffrey I. Webb

We refer to this problem as Time Series Extrinsic Regression (TSER), where we are interested in a more general methodology of predicting a single continuous value, from univariate or multivariate time series.

Benchmarking regression +4

TS-CHIEF: A Scalable and Accurate Forest Algorithm for Time Series Classification

2 code implementations25 Jun 2019 Ahmed Shifaz, Charlotte Pelletier, Francois Petitjean, Geoffrey I. Webb

We demonstrate that TS-CHIEF can be trained on 130k time series in 2 days, a data quantity that is beyond the reach of any TSC algorithm with comparable accuracy.

Attribute General Classification +3

Temporal Convolutional Neural Network for the Classification of Satellite Image Time Series

1 code implementation26 Nov 2018 Charlotte Pelletier, Geoffrey I. Webb, Francois Petitjean

The experimental results show that TempCNNs are more accurate than RF and RNNs, that are the current state of the art for SITS classification.

Classification General Classification +3

Proximity Forest: An effective and scalable distance-based classifier for time series

4 code implementations31 Aug 2018 Benjamin Lucas, Ahmed Shifaz, Charlotte Pelletier, Lachlan O'Neill, Nayyar Zaidi, Bart Goethals, Francois Petitjean, Geoffrey I. Webb

We demonstrate on a 1M time series Earth observation dataset that Proximity Forest retains this accuracy on datasets that are many orders of magnitude greater than those in the UCR repository, while learning its models at least 100, 000 times faster than current state of the art models Elastic Ensemble and COTE.

Attribute Earth Observation +4

Elastic bands across the path: A new framework and methods to lower bound DTW

1 code implementation29 Aug 2018 Chang Wei Tan, Francois Petitjean, Geoffrey I. Webb

One of the key time series classification algorithms, the nearest neighbor algorithm with DTW distance (NN-DTW) is very expensive to compute, due to the quadratic complexity of DTW.

Clustering Dynamic Time Warping +4

On the Inter-relationships among Drift rate, Forgetting rate, Bias/variance profile and Error

1 code implementation29 Jan 2018 Nayyar A. Zaidi, Geoffrey I. Webb, Francois Petitjean, Germain Forestier

These hypotheses lead to the concept of the sweet path, a path through the 3-d space of alternative drift rates, forgetting rates and bias/variance profiles on which generalization error will be minimized, such that slow drift is coupled with low forgetting and low bias, while rapid drift is coupled with fast forgetting and low variance.

Accurate parameter estimation for Bayesian Network Classifiers using Hierarchical Dirichlet Processes

4 code implementations25 Aug 2017 Francois Petitjean, Wray Buntine, Geoffrey I. Webb, Nayyar Zaidi

The main result of this paper is to show that improved parameter estimation allows BNCs to outperform leading learning methods such as Random Forest for both 0-1 loss and RMSE, albeit just on categorical datasets.

General Classification

Characterizing Concept Drift

no code implementations12 Nov 2015 Geoffrey I. Webb, Roy Hyde, Hong Cao, Hai Long Nguyen, Francois Petitjean

This supports the development of the first comprehensive set of formal definitions of types of concept drift.

Deep Broad Learning - Big Models for Big Data

no code implementations4 Sep 2015 Nayyar A. Zaidi, Geoffrey I. Webb, Mark J. Carman, Francois Petitjean

For some learning tasks there is power in learning models that are not only Deep but also Broad.

Skopus: Mining top-k sequential patterns under leverage

1 code implementation26 Jun 2015 Francois Petitjean, Tao Li, Nikolaj Tatti, Geoffrey I. Webb

It combines (1) a novel definition of the expected support for a sequential pattern - a concept on which most interestingness measures directly rely - with (2) SkOPUS: a new branch-and-bound algorithm for the exact discovery of top-k sequential patterns under a given measure of interest.

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