def _find_obj_pos()

in data/envs/babyai/bot_agent.py [0:0]

• 31 lines of code
• 22 McCabe index (conditional complexity)

    def _find_obj_pos(self, obj_desc, adjacent=False):
        """Find the position of the closest visible object matching a given description."""

        assert len(obj_desc.obj_set) > 0

        best_distance_to_obj = 999
        best_pos = None
        best_obj = None

        for i in range(len(obj_desc.obj_set)):
            if obj_desc.obj_set[i].type == "wall":
                continue
            try:
                if obj_desc.obj_set[i] == self.mission.unwrapped.carrying:
                    continue
                obj_pos = obj_desc.obj_poss[i]

                if self.vis_mask[obj_pos]:
                    shortest_path_to_obj, _, with_blockers = self._shortest_path(
                        lambda pos, cell: pos == obj_pos, try_with_blockers=True
                    )
                    assert shortest_path_to_obj is not None
                    distance_to_obj = len(shortest_path_to_obj)

                    if with_blockers:
                        # The distance should take into account the steps necessary
                        # to unblock the way. Instead of computing it exactly,
                        # we can use a lower bound on this number of steps
                        # which is 4 when the agent is not holding anything
                        # (pick, turn, drop, turn back
                        # and 7 if the agent is carrying something
                        # (turn, drop, turn back, pick,
                        # turn to other direction, drop, turn back)
                        distance_to_obj = len(shortest_path_to_obj) + (7 if self.mission.unwrapped.carrying else 4)

                    # If we looking for a door and we are currently in that cell
                    # that contains the door, it will take us at least 2
                    # (3 if `adjacent == True`) steps to reach the goal.`
                    if distance_to_obj == 0:
                        distance_to_obj = 3 if adjacent else 2

                    # If what we want is to face a location that is adjacent to an object,
                    # and if we are already right next to this object,
                    # then we should not prefer this object to those at distance 2
                    if adjacent and distance_to_obj == 1:
                        distance_to_obj = 3

                    if distance_to_obj < best_distance_to_obj:
                        best_distance_to_obj = distance_to_obj
                        best_pos = obj_pos
                        best_obj = obj_desc.obj_set[i]
            except IndexError:
                # Suppose we are tracking red keys, and we just used a red key to open a door,
                # then for the last i, accessing obj_desc.obj_poss[i] will raise an IndexError
                # -> Solution: Not care about that red key we used to open the door
                pass

        return best_obj, best_pos