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Journal of Information Science and Engineering, Vol. 30 No. 4, pp. 1483-1503 (September 2014)


A Hybrid Method for Sequence Clustering*


JIA-LIEN HSU1,+, YU-SHU WU2 AND I-CHIN WU2
1Department of Computer Science and Information Engineering
2Department of Information Management
Fu Jen Catholic University
New Taipei City, 242 Taiwan

The problem of sequence clustering is one of the fundamental research topics. However, most algorithms are dedicated to the case of single-label clustering. In this paper, we propose sequence clustering algorithms which can be applied for finding multi labels with respect to variable-length sequences. In our research, we first map sequences as vectors in the feature space by applying DCT transformation on each sliding window of sequences. A large amount of feature vectors could be further reduced by using the histogram concept and the quantization technique. Then, we use the hierarchical clustering algorithm to determine sequence labels. We also apply minimum bounding rectangle (MBR) techniques to approximate the distribution of feature vectors, and the elapsed time can be reduced accordingly. According to our experiment, the accuracy in the Rand index validity can be up to 88% for the single-label clustering of equal-length case. By applying the MBR techniques, the elapsed time of improved approach can be reduced as much as one sixth of the original approach, and the accuracy remains 86%. For the multi- label clustering, the accuracy can be up to 85%, and the elapsed time is about one fifth of the single-label case.

Keywords: sequence clustering, multi-label, subsequence, variable-length sequence, quantization

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Received January 14, 2013; revised March 20, 2013; accepted April 10, 2013.
Communicated by Hsin-Min Wang.
+ Corresponding author: alien@csie.fju.edu.tw.
* This research was supported by Fu Jen Catholic University with Project No. 410031044042, and sponsored by the National Science Council under Contract No. NSC-100-2221-E-030-021 and NSC-101-2221-E-030-008.