log if shield cannot provide mask

examples/shields/rl/sb3utils.py

@@ -36,7 +36,7 @@ class MiniGridSbShieldingWrapper(gym.core.Wrapper):
 
     def step(self, action):
         obs, rew, done, truncated, info = self.env.step(action)
-
+        info["no_shield_action"] = not self.shield.has_key(self.env.get_symbolic_state())
         return obs, rew, done, truncated, info
 
 def parse_sb3_arguments():
@@ -104,6 +104,7 @@ class InfoCallback(BaseCallback):
         self.sum_collisions = 0
         self.sum_opened_door = 0
         self.sum_picked_up = 0
+        self.no_shield_action = 0
 
     def _on_step(self) -> bool:
         infos = self.locals["infos"][0]
@@ -125,4 +126,8 @@ class InfoCallback(BaseCallback):
             if infos["picked_up"]:
                 self.sum_picked_up += 1
             self.logger.record("info/sum_picked_up", self.sum_picked_up)
+        if "no_shield_action" in infos:
+            if infos["no_shield_action"]:
+                self.no_shield_action += 1
+            self.logger.record("info/no_shield_action", self.no_shield_action)
         return True