Add substructure with radius rooted at atom to shingling as SMILES Add substructure of ring to shingling as SMILES 9: end for We applied the same hyperparameter values (n estimators=999999, learning rate=0.01, max depth=15, min child weight=8, colsample bytree=0.2125, subsample=1) in all uses of xgboost. For each test, 10% of the training data were randomly selected as the validation set an removed from the training set. The validation data sets were used as evaluation sets for early stopping (20 rounds for all data sets with the exception of the USPTO, data for which 10 rounds were used to speed up the calculation).