Figure : XLogP values versus the molecular weight for the RPLC classification test set. In blue are the correctly classified 'outside' cases, in green are the correctly classified 'inside' and 'maybe' cases, in orange are the wrongly classified 'inside' cases as 'maybe' and vice versa, in red the wrongly classified 'inside' and 'maybe' cases as 'outside' and the wrongly classified 'outside' cases as 'inside'. The star markers show the compounds that were outside the 95% applicability domain of the RPLC classification training set A total of 280 features were contributing to the RPLC classification model. This is more than for each of the three r i regression models, which was expected due to the higher variety in chemical structures used in the RPLC classification model. The 20 most contributing features are mainly described by ring related features and distances between combinations C, N, and O atoms. A previous version of the model that was tested, using only the 2DAPC fingerprints, frequently wrongly classified 'inside' as 'outside' due to the high degree of cyclicity in the chemical structures (e.g., peimine). Hence, the addition of the reduced PubChem fingerprints better captures these chemical properties. As a result, the number or rings with a size of 6, the minimum number of aromatic rings, and the number of rings with a size of 5 were also part of the top 20 most contributing features.