Importance values of top 20 features for the best models in the multi-class and one vs all approach: (a and b) XGBoost; (c and d) LightGBM. The importance values (x-axis) are presented in logarithmic scale for ease of visualisation. The x-axis scale also varies based on the algorithm being used. The feature names are shown on the y-axis. The variable imp_z is the final photo-z prediction value and oof_flag_outlier is the binary variable that identifies the out-of-fold photo-z catastrophic outliers.