UMAP dimensionality reduction from the 12D space of features to 2D. Left: dimensionality reduction of the PMS and classical Be candidates, together with those sources which belong to either category (i.e. p(PMS)+p(CBe)≥50% but p(PMS) < 50%, p(CBe) < 50%). Right: we project the known Herbig Ae/Be, T-Tauri, and classical Be stars used for the training onto the same plane, which is colour-coded following the PMS probability distribution of the sources at left.