Distributions of the CSNet training and the testing samples in the planes of T_eff–log g, T_eff–[Fe/H], [BP–RP]–G, [α/Fe]–[Fe/H], [C/Fe]–[Fe/H], [N/Fe]–[Fe/H], [Mg/Fe]–[Fe/H], [Ca/Fe]–[Fe/H], [C/N]–[Fe/H], [C/α]–[Fe/H], [Mg/α]–[Fe/H], and [Ca/α]–[Fe/H], from top to bottom and left to right. The black and red dots represent the training set and testing set stars, respectively. To avoid crowding, only 10 per cent of the selected stars are plotted.