Set ndcg to default for LTR. (#8822)

- Add document. - Add tests. - Use `ndcg` with `topk` as default.
2023-06-09 23:31:33 +08:00
parent e4dd6051a0
commit 1fcc26a6f8
18 changed files with 842 additions and 19 deletions
--- a/tests/python/test_eval_metrics.py
+++ b/tests/python/test_eval_metrics.py
@@ -299,7 +299,9 @@ class TestEvalMetrics:
    def run_pr_auc_ltr(self, tree_method):
        from sklearn.datasets import make_classification
        X, y = make_classification(128, 4, n_classes=2, random_state=1994)
-        ltr = xgb.XGBRanker(tree_method=tree_method, n_estimators=16)
+        ltr = xgb.XGBRanker(
+            tree_method=tree_method, n_estimators=16, objective="rank:pairwise"
+        )
        groups = np.array([32, 32, 64])
        ltr.fit(
            X,