Store CV results if any (#91)

* Store CV results if any

When using a `GridSearchCV` or equivalent as estimator, it is often useful to have access to CV results. This is of particular importance when having multiple scorers, as otherwise it is not possible to access the other scorers results.

* Fix checks

Checks were done badly and failed if the returned object was an empty container or 0.

Author: vnmabus

skdatasets/utils/experiment.py

@@ -213,11 +213,19 @@ def _benchmark_from_data(
         _append_info(experiment, "fitted_estimator", estimator)
 
     best_params = getattr(estimator, "best_params_", None)
-    if best_params:
+    if best_params is not None:
         _append_info(experiment, "search_best_params", best_params)
 
+    best_index = getattr(estimator, "best_index_", None)
+    if best_index is not None:
+        _append_info(experiment, "search_best_index", best_index)
+
+    cv_results = getattr(estimator, "cv_results_", None)
+    if cv_results is not None:
+        _append_info(experiment, "search_cv_results", cv_results)
+
     best_score = getattr(estimator, "best_score_", None)
-    if best_params:
+    if best_score is not None:
         _append_info(experiment, "search_best_score", best_score)
 
     with _add_timing(experiment, "score_time"):