In this grouped split, similar structures labeled using the chemical formula of the MOFs are always grouped in either the training or the test set, hence avoiding the aforementioned problem. Doing so, we did not notice any significant alteration of the generalization error, which we attribute to the high number and the diversity of the structures we are deadling with. The goal is to learn from the training set a relationship between the descriptors and the target ambient-pressure selectivity in order to evaluate the performance on the test set.