“…For example, Ferstl et al 12 use PCA to convert streamlines into a structure preserving Euclidean space. Furthermore, a lot of approaches are implemented by feature extraction algorithms like k-series in the work 5,36,6 , and the work based on DBSCAN 10,26 , AHC 12,13,37,38,39,40 and topic modeling 41,42,43,44,45,46,47,48,49,50,51,52,53 .…”