Results of the inference of the ANN-R3292-2 for all stars (left, green) and the ANN-R4290-2 only for giants (right, blue) for the test set. The upper panels show the predictions vs the spectroscopic metallicities, and the lower panels show the residual for the metallicities. The grey area indicates a range of ±1 in standard deviation, which is 0.1 (dex) for all stars and 0.07 (dex) for giants only. The residuals were calculated as the difference between the predictions and the spectroscopic metallicities.