build_anti_testset() optimization (#106)

Move user_items list out of the iteration.
NicolasHug · Nov 14, 2017 · 77d728b · 77d728b
1 parent e8a173c
commit 77d728b
Showing 1 changed file with 4 additions and 6 deletions.
diff --git a/surprise/dataset.py b/surprise/dataset.py
@@ -694,12 +694,10 @@ def build_anti_testset(self, fill=None):
 
         anti_testset = []
         for u in self.all_users():
-            for i in self.all_items():
-                user_items = [j for (j, _) in self.ur[u]]
-                if i not in user_items:
-                    r_ui = (self.to_raw_uid(u), self.to_raw_iid(i),
-                            fill)
-                    anti_testset.append(r_ui)
+            user_items = set([j for (j, _) in self.ur[u]])
+            anti_testset += [(self.to_raw_uid(u), self.to_raw_iid(i), fill) for
+                             i in self.all_items() if
+                             i not in user_items]
         return anti_testset
 
     def all_users(self):