Improve state file naming convention.

climax/core/dataset.py

@@ -122,8 +122,17 @@ class EoDataset(torch.utils.data.Dataset):
         Spredictors = ''.join([ERA5_S_VARIABLE_NAME[p] for p in predictors if p
                                in ERA5_S_VARIABLE_NAME])
         plevels = [str(p) for p in plevels]
-        state_file = '_'.join([model.__name__, str(predictand), Ppredictors,
-                               *plevels, Spredictors])
+        state_file = '_'.join([model.__name__, str(predictand)])
+
+        # check if predictors on pressure levels are used
+        state_file = ('_'.join([state_file, Ppredictors, *plevels]) if
+                      any([p in ERA5_P_VARIABLE_NAME for p in predictors]) else
+                      state_file)
+
+        # check if predictors on surface are used
+        state_file = ('_'.join([state_file, Spredictors]) if
+                      any([p in ERA5_S_VARIABLE_NAME for p in predictors]) else
+                      state_file)
 
         # check whether digital elevation model, slope and aspect, and the day
         # of year were used