LightGBM tree outputs

lgbm_tree_outputs.py

import lightgbm as lgb
from sklearn import datasets
from sklearn import model_selection

X, y = datasets.load_boston(return_X_y=True)
X_fit, X_val, y_fit, y_val

model = lgb.LGBMRegressor()
model.fit(X_fit, y_fit)

y_pred = model.predict(X_val)

y_pred_all = np.array([
    [
        model._Booster.get_leaf_output(tree_id, leaf_id) 
        for tree_id, leaf_id in enumerate(indexes)
    ]
    for indexes in leaf_ids
])

assert sum(y_pred_all[0]) == y_pred[0]