PCA analysis with magnitudes of motion indicated by arrow length and color

[kolmorgan]

I want to perform the PCA analysis and get results with the magnitudes of motion indicated by arrow length and color as quoted, and I saw the "color arrow by mobility issue was closed with #38 before", but I don't know how to do it. Can you tell me how to do it if possible? Thanks. (The quoted figure and its legend were shown below)

"Principal component analysis of both TLR4 chains in the complex when bound to LPA, 33 PA, and 53 PA (the MD-2 chains are omitted for clarity). The dominant, collective mode of motion for each Ca atom is represented by an arrow, with the magnitudes of motion indicated by arrow length and color according to the inset key, in distance units of Ångstroms. The data in (I) were plotted using VMD (visual molecular dynamics) (Humphrey et al., 1996) and represent an interpolation between the two extreme projections around the average TLR4 structure, after projection of the trajectory onto the first eigenvector." #