A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data

A large amount of time series data is being generated every day in a wide range of sensor application domains. The symbolic aggregate approximation (SAX) is a well-known time series representation method, which has a lower bound to Euclidean distance and may discretize continuous time series. SAX ha...

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Main Authors: Zhenwen He, Shirong Long, Xiaogang Ma, Hong Zhao
Format: Article
Language:English
Published: MDPI AG 2020-11-01
Series:Algorithms
Subjects:
Online Access:https://www.mdpi.com/1999-4893/13/11/284
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author Zhenwen He
Shirong Long
Xiaogang Ma
Hong Zhao
author_facet Zhenwen He
Shirong Long
Xiaogang Ma
Hong Zhao
author_sort Zhenwen He
collection DOAJ
description A large amount of time series data is being generated every day in a wide range of sensor application domains. The symbolic aggregate approximation (SAX) is a well-known time series representation method, which has a lower bound to Euclidean distance and may discretize continuous time series. SAX has been widely used for applications in various domains, such as mobile data management, financial investment, and shape discovery. However, the SAX representation has a limitation: Symbols are mapped from the average values of segments, but SAX does not consider the boundary distance in the segments. Different segments with similar average values may be mapped to the same symbols, and the SAX distance between them is 0. In this paper, we propose a novel representation named SAX-BD (boundary distance) by integrating the SAX distance with a weighted boundary distance. The experimental results show that SAX-BD significantly outperforms the SAX representation, ESAX representation, and SAX-TD representation.
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spelling doaj.art-899e8d83f76140c186abca16f08d2ef52023-11-20T20:15:02ZengMDPI AGAlgorithms1999-48932020-11-01131128410.3390/a13110284A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series DataZhenwen He0Shirong Long1Xiaogang Ma2Hong Zhao3School of Computer Science, China University of Geosciences (Wuhan), 388 Lumo Road, Wuhan 430074, ChinaSchool of Computer Science, China University of Geosciences (Wuhan), 388 Lumo Road, Wuhan 430074, ChinaDepartment of Computer Science, University of Idaho, 875 Perimeter Drive MS 1010, Moscow, ID 83844-1010, USASchool of Computer Science, China University of Geosciences (Wuhan), 388 Lumo Road, Wuhan 430074, ChinaA large amount of time series data is being generated every day in a wide range of sensor application domains. The symbolic aggregate approximation (SAX) is a well-known time series representation method, which has a lower bound to Euclidean distance and may discretize continuous time series. SAX has been widely used for applications in various domains, such as mobile data management, financial investment, and shape discovery. However, the SAX representation has a limitation: Symbols are mapped from the average values of segments, but SAX does not consider the boundary distance in the segments. Different segments with similar average values may be mapped to the same symbols, and the SAX distance between them is 0. In this paper, we propose a novel representation named SAX-BD (boundary distance) by integrating the SAX distance with a weighted boundary distance. The experimental results show that SAX-BD significantly outperforms the SAX representation, ESAX representation, and SAX-TD representation.https://www.mdpi.com/1999-4893/13/11/284time seriesSAXESAXSAX-TDSAX-BD
spellingShingle Zhenwen He
Shirong Long
Xiaogang Ma
Hong Zhao
A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data
Algorithms
time series
SAX
ESAX
SAX-TD
SAX-BD
title A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data
title_full A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data
title_fullStr A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data
title_full_unstemmed A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data
title_short A Boundary Distance-Based Symbolic Aggregate Approximation Method for Time Series Data
title_sort boundary distance based symbolic aggregate approximation method for time series data
topic time series
SAX
ESAX
SAX-TD
SAX-BD
url https://www.mdpi.com/1999-4893/13/11/284
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