Figure 3: Unsupervised learning techniques (e.g., hierarchical
clustering, tree classification) can be used for clustering analysis.
This hierarchical clustering was constructed based on Euclidean distance
(between T1 relaxation and T2relaxation) and its´ quantitative linkages (e.g., inter/intra cluster
similarity) shown in a heat map. (A, A´, B, B´, C, C´, C´´, D) were the
variants of the same oil content taken from different manufacturers.
Tree classification method is shown for comparison (Supp. Fig. 2).