Merge pull request #1811 from gro1m/gro1m/replace-append-with-pd-concat

replace append with pd.concat

recommenders/models/deeprec/DataModel/ImplicitCF.py

@@ -70,7 +70,7 @@ def _data_processing(self, train, test):
             list: train and test pandas.DataFrame Dataset, which have been reindexed and filtered.
 
         """
-        df = train if test is None else train.append(test)
+        df = train if test is None else pd.concat([train, test],axis=0,ignore_index=True)
 
         if self.user_idx is None:
             user_idx = df[[self.col_user]].drop_duplicates().reindex()