In total 135,455 distinct reactions passed these filters. Random splitting was used to generate 80/10/10 training (101,236 reactions), validation (12,139), and testing splits (12,139). The splits included only one direction of each reaction (i.e., the data was not augmented by including the reverse versions of reactions in training or testing). Unless otherwise stated, all accuracies are reported for prediction accuracy on the RGD1 testing set.