Fig. 12: SHAP-LOWESS main effect curves and threshold characteristics of key cost factors.
From: Machine-learning-based reconstruction of Ming-dynasty defensive corridors in Yuxian
a–f correspond to the main effect curves of the top six factors in terms of contribution degree respectively. The purple scatter points represent sample-level SHAP values, where the shade of color indicates the magnitude of factor values; the solid purple line denotes the LOWESS-based smoothed curve; the black dashed line is the SHAP = 0 baseline; the green dashed lines mark the threshold positions where the main effect shifts from negative to positive or where there are significant changes in slope gradient. The light purple shaded areas represent relatively unfavorable value ranges, which are used to define the effective response intervals of each cost factor and their preference directions for potential defense corridors.
