1 code implementation • 20 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.
1 code implementation • 14 Feb 2021 • Geoffrey I. Webb, Francois Petitjean
Due to DTW's high computation time, lower bounds are often employed to screen poor matches.
no code implementations • 12 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.
1 code implementation • 27 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.
1 code implementation • 23 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.
2 code implementations • 19 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.
no code implementations • 10 Oct 2019 • Chang Wei Tan, Francois Petitjean, Eamonn Keogh, Geoffrey I. Webb
Research into time series classification has tended to focus on the case of series of uniform length.
2 code implementations • 25 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.
1 code implementation • 26 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.
4 code implementations • 31 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.
1 code implementation • 29 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.
1 code implementation • 29 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.
4 code implementations • 25 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.
no code implementations • 12 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.
no code implementations • 4 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.
1 code implementation • 26 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.