Affiliations: [a] Department of Computer Science and Engineering, University of Texas at Arlington, Arlington, TX, USA | [b] Department of Computer and Systems Sciences, Stockholm University, Stockholms, Sweden
Correspondence:
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Corresponding author: Alexios Kotsifakos, Department of Computer Science and Engineering, University of Texas at Arlington, Arlington, TX, USA. E-mail:alexios.kotsifakos@mavs.uta.edu
Abstract: Many distance or similarity measures have been proposed for time series similarity search. However, none of these measures is guaranteed to be optimal when used for 1-Nearest Neighbor (NN) classification. In this paper we study the problem of selecting the most appropriate distance measure, given a pool of time series distance measures and a query, so as to perform NN classification of the query. We propose a framework for solving this problem, by identifying, given the query, the distance measure most likely to produce the correct classification result for that query. From this proposed framework, we derive three specific methods, that differ from each other in the way they estimate the probability that a distance measure correctly classifies a query object. In our experiments, our pool of measures consists of Dynamic Time Warping (DTW), Move-Split-Merge (MSM), and Edit distance with Real Penalty (ERP). Based on experimental evaluation with 45 datasets, the best-performing of the three proposed methods provides the best results in terms of classification error rate, compared to the competitors, which include using the Cross Validation method for selecting the distance measure in each dataset, as well as using
a single specific distance measure (DTW, MSM, or ERP) across all datasets.
Keywords: Time series, classification, distance measures
