fix base validation K without cutoffs

elliot/recommender/base_recommender_model.py

@@ -32,16 +32,17 @@ def __init__(self, data, config, params, *args, **kwargs):
 
         self._restore = getattr(self._params.meta, "restore", False)
 
+        _cutoff_k = getattr(data.config.evaluation, "cutoffs", [data.config.top_k])
+        _cutoff_k = _cutoff_k if isinstance(_cutoff_k, list) else [_cutoff_k]
         _first_metric = data.config.evaluation.simple_metrics[0] if data.config.evaluation.simple_metrics else ""
-        self._validation_metric = getattr(self._params.meta, "validation_metric", _first_metric + "@10").split("@")
+        _default_validation_k = getattr(data.config.evaluation, "cutoffs", [data.config.top_k])[0]
+        self._validation_metric = getattr(self._params.meta, "validation_metric",
+                                          _first_metric + "@" + str(_default_validation_k)).split("@")
         if self._validation_metric[0].lower() not in [m.lower()
-                                              for m in data.config.evaluation.simple_metrics]:
+                                                      for m in data.config.evaluation.simple_metrics]:
             raise Exception("Validation metric must be in the list of simple metrics")
 
-        _cutoff_k = getattr(data.config.evaluation, "cutoffs", [data.config.top_k])
-        _cutoff_k = _cutoff_k if isinstance(_cutoff_k, list) else [_cutoff_k]
         self._validation_k = int(self._validation_metric[1]) if len(self._validation_metric) > 1 else _cutoff_k[0]
-
         if self._validation_k not in _cutoff_k:
             raise Exception("Validation cutoff must be in general cutoff values")