Figure 4. Mode of action can be resolved within compound classes.

1. The confusion matrix showing cross‐validation performance of a classifier trained to distinguish serotonin receptor antagonists from each other. Ritanserin is distinguishable from all other compounds, and the two structurally similar antidepressants (mianserin and methiothepin) are somewhat mutually confused by the classifier but are distinguishable from the non‐antidepressants.
2. The confusion matrix for the mitochondrial inhibitors also shows some substructure: complex II and III inhibitors (cyazofamid, antimycin, cyenopyrafen) are phenotypically similar, and distinct from the complex I inhibitors.