Fig 2. Procedure of the proposed graph-based subsequence anomaly detection (GraphTS).

(a) An example time series T extracted from MITBIH 1 dataset, with four anomalous subsequences (highlighted in red areas). (b) 2DSTS visualization of time series (step 1). (c) Graph construction (step 2). (d) Subsequence anomaly detection using subsequence score curves for all subsequences of T: low score indicates anomalous subsequences (step 3).