Update Mimic4Dataset.py

Mimic4Dataset.py

@@ -450,7 +450,7 @@ class Mimic4Dataset(datasets.GeneratorBasedBuilder):
             if feat_tocsv:
                 #save the features of the vector for analysis purposes if needed
                 if self.encoding == 'concat':
-                    feats = concat_cols
+                    feats = concat_cols.copy()
                 else:
                     feats = list(dyn_df.columns.droplevel(0))
                 feats.extend(list(cond_df.columns))