initial changes to crossings. Now not detected anymore as unusable switches

flatland/envs/observations.py

@@ -347,6 +347,14 @@ class TreeObsForRailEnv(ObservationBuilder):
                     # Cummulate the number of agents on branch with other direction
                     other_agent_opposite_direction += 1
 
+            # Check number of possible transitions for agent and total number of transitions in cell (type)
+            cell_transitions = self.env.rail.get_transitions(*position, direction)
+            transition_bit = bin(self.env.rail.get_full_transitions(*position))
+            total_transitions = transition_bit.count("1")
+            crossing_found = False
+            if int(transition_bit, 2) == int('1000010000100001', 2):
+                crossing_found = True
+
             # Register possible future conflict
             if self.predictor and num_steps < self.max_prediction_depth:
                 int_position = coordinate_to_position(self.env.width, [position])
@@ -354,7 +362,7 @@ class TreeObsForRailEnv(ObservationBuilder):
                     pre_step = max(0, tot_dist - 1)
                     post_step = min(self.max_prediction_depth - 1, tot_dist + 1)
 
-                    # Look for opposing paths at distance num_step
+                    # Look for conflicting paths at distance num_step
                     if int_position in np.delete(self.predicted_pos[tot_dist], handle, 0):
                         conflicting_agent = np.where(self.predicted_pos[tot_dist] == int_position)
                         for ca in conflicting_agent[0]:
@@ -362,7 +370,8 @@ class TreeObsForRailEnv(ObservationBuilder):
                                 potential_conflict = tot_dist
                             if self.env.dones[ca] and tot_dist < potential_conflict:
                                 potential_conflict = tot_dist
-                    # Look for opposing paths at distance num_step-1
+
+                    # Look for conflicting paths at distance num_step-1
                     elif int_position in np.delete(self.predicted_pos[pre_step], handle, 0):
                         conflicting_agent = np.where(self.predicted_pos[pre_step] == int_position)
                         for ca in conflicting_agent[0]:
@@ -370,7 +379,8 @@ class TreeObsForRailEnv(ObservationBuilder):
                                 potential_conflict = tot_dist
                             if self.env.dones[ca] and tot_dist < potential_conflict:
                                 potential_conflict = tot_dist
-                    # Look for opposing paths at distance num_step+1
+
+                    # Look for conflicting paths at distance num_step+1
                     elif int_position in np.delete(self.predicted_pos[post_step], handle, 0):
                         conflicting_agent = np.where(self.predicted_pos[post_step] == int_position)
                         for ca in conflicting_agent[0]:
@@ -398,12 +408,8 @@ class TreeObsForRailEnv(ObservationBuilder):
                 last_is_target = True
                 break
 
-            cell_transitions = self.env.rail.get_transitions(*position, direction)
-            transition_bit = bin(self.env.rail.get_full_transitions(*position))
-            total_transitions = transition_bit.count("1")
-
             # Check if crossing is found --> Not an unusable switch
-            if int(transition_bit, 2) == int('1000010000100001', 2):
+            if crossing_found:
                 # Treat the crossing as a straight rail cell
                 total_transitions = 2
             num_transitions = np.count_nonzero(cell_transitions)