International
Tables for Crystallography Volume H Powder diffraction Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk © International Union of Crystallography 2018 
International Tables for Crystallography (2018). Vol. H, ch. 3.8, pp. 335336
Figure 3.8.9^{a} 

Figure 3.8.9
The complete cluster analysis for the aspirin samples. (a) The correlation matrix, which is the source of all the clustering results. The entries are colour coded: the darker the shade, the higher the correlation. (b) The dendrogram. The colours assigned to the samples are used in all the visualization tools. (c) The corresponding MMDS plot. The clustering defined by the dendrogram is well defined. (d) The piechart view. (e) The minimum spanning tree. (f) The scree plot. It indicates that three clusters explain 95% of the variance of the distance matrix derived from (a). (g–i) The silhouettes for the red, the orange and the green clusters, respectively. These are discussed in detail in the caption to Fig. 3.8.8. (j) The default parallelcoordinates plot. The clusters are well maintained into the 4th, 5th and 6th dimensions. (k) Another view of the parallel coordinates using the grand tour. The clustering remains well maintained in higher dimensions. 