We applied PCA to visualize the magnitude of the effect of each functional group at the possible locations on the catalysts (Figure ). Each substitution location is depicted with a circle over the hydrogen on the original catalyst; the size of the circle corresponds to how much the intermediate reaction energies changed summed over all substitutions at that location. The circles are split into three colors that each correspond to the first three principal components, where the fraction of the circle is proportional to the magnitude of that principal component's contribution at that site (see SI section 2 for a mathematical description).