Asynchronism-based principal component analysis for time
series data mining
Hailin Li
⇑
College of Business Administration, Huaqiao University, Quanzhou 362021, China
article info
Keywords:
Asynchronous correlation
Covariance matrix
Principal component analysis
Time series data mining
Dynamic time warping
abstract
Principal component analysis (PCA) is often applied to dimensionality reduction for time series data min-
ing. However, the principle of PCA is based on the synchronous covariance, which is not very effective in
some cases. In this paper, an asynchronism-based principal component analysis (APCA) is proposed to
reduce the dimensionality of univariate time series. In the process of APCA, an asynchronous method
based on dynamic time warping (DTW) is developed to obtain the interpolated time series which derive
from the original ones. The correlation coefficient or covariance between the interpolated time series rep-
resents the correlation between the original ones. In this way, a novel and valid principal component
analysis based on the asynchronous covariance is achieved to reduce the dimensionality. The results of
several experiments demonstrate that the proposed approach APCA outperforms PCA for dimensionality
reduction in the field of time series data mining.
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
Time series is one kind of the most important research objects
in the field of data mining. The techniques used in this data is
called time series data mining (TSDM) (Esling & Agon, 2012). How-
ever, since its high dimensionality often renders standard data
mining techniques inefficient, the methods used to reduce the
dimensionality are devised.
So far, there exists many methods to resolve this problem,
which are considered as two kinds of dimensionality reduction.
One is based on univariate time series, such as discrete Fourier
transformation (DFT) (Agrawal, Faloutsos, & Swami, 1993), discrete
wavelet transformation (DWT) (Maharaj & Urso, 2011; Struzik &
Siebes, 1998, 1999), polynomial representation (PR) (Fuchs,
Gruber, Pree, & Sick, 2010), piecewise linear approximation (PLA)
(Keogh, Chu, Hart, & Pazzani, 2001; Papadakis & Kaburlasos,
2010; Shatkay & Zdonik, 1996), piecewise aggregate approxima-
tion (PAA) (Keogh, Chakrabarti, Pazzani, & Mehrotra, 2000; Li &
Guo, 2011), symbolic aggregate approximation (SAX) (Lee, Wu, &
Lee, 2009; Lin, Keogh, Lonardi, & Chiu, 2003). These methods are
mainly proposed to reduced dimensionality from the points of
univariate time series. In other word, they mainly concentrate on
the transformation of a single time series so that the dimension
of the reduced representations is lower than that of the original
one. The other is based on the time series dataset, such as singular
value decomposition (SVD) (Spiegel, Gaebler, & Lommatzsch,
2011), principal component analysis (PCA) (Singhal & Seborg,
2002) and independent component analysis (ICA) (Cichocki &
Amari, 2002).
SVD and PCA are often seen as the same method to retain the
first several principal components and to represent the whole
dataset. However, ICA is the development of principal component
analysis and factor analysis. In the field of time series data mining,
the methods are often used and combined with the corresponding
measurements to discover the information and knowledge from
time series dataset. Krzanowski (1979) used PCA to construct the
principal components and chosen the first k principal components
to represent the multivariate time series. At the same time, the
similarity between two time series are calculated by using the co-
sine value of the angle between the corresponding principal com-
ponents. Singhal and Seborg (2005) proposed a new approach S
dist
to compute the similarity based on PCA, which is better than the
earlier methods. Karamitopoulos and Evangelidis (2010) used
PCA to construct the feature space of the queried time series and
projected every time series to the space. They computed the error
between two reconstructed time series as the distance between
the query time series and the queried one. SVD is often based on
PCA, which uses KL decomposition method to reduce the dimen-
sionality of time series. Li, Khan, and Prabhakaran (2006) proposed
two methods to choose the feature vectors and used them to clas-
sify time series. Weng and Shen (2008) extended the traditional
SVD to an two-dimensional SVD (2dSVD) that extracts the princi-
pal components from the column–column and row–row directions
to compute the covariance matrix. Since feature extraction is one
of the most importance tasks for ICA, it was applied to the analysis
of time series. Wu and Yu (2005) used FastICA (Hyvärinen, 1999)to
0957-4174/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.eswa.2013.10.019
⇑
Tel.: +86 595 22693815.
E-mail address: hailin@mail.dlut.edu.cn
Expert Systems with Applications 41 (2014) 2842–2850
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