Subplots (a) and (b) show the mean errors (ME) of S 1 and T 1 , while (c) and (d) show mean absolute errors (MAE). As seen, the red/yellow/green clusters are likely to have low error, while the purple/dark green clusters have high error. While this analysis is generally useful, the mapping and clustering approach requires knowing the location and cluster categorization of a specific molecule in global chemical space. Oftentimes, this is not known, or would require significant computation.