improved city orientation with grid_mode=True

examples/flatland_2_0_example.py

@@ -30,9 +30,9 @@ speed_ration_map = {1.: 0.25,  # Fast passenger train
 
 env = RailEnv(width=50,
               height=50,
-              rail_generator=sparse_rail_generator(num_cities=8,  # Number of cities in map (where train stations are)
+              rail_generator=sparse_rail_generator(num_cities=12,  # Number of cities in map (where train stations are)
                                                    seed=1,  # Random seed
-                                                   grid_mode=False,
+                                                   grid_mode=True,
                                                    max_inter_city_rails=2,
                                                    max_tracks_in_city=4,
                                                    ),

flatland/envs/rail_generators.py

@@ -692,7 +692,10 @@ def sparse_rail_generator(num_cities=5, grid_mode=False, max_inter_city_rails=4,
             # Store the directions to these neighbours and orient city to face closest neighbour
             connection_sides_idx = []
             idx = 1
-            current_closest_direction = direction_to_point(node_position, node_positions[closest_neighb_idx[idx]])
+            if grid_mode:
+                current_closest_direction = np.random.randint(4)
+            else:
+                current_closest_direction = direction_to_point(node_position, node_positions[closest_neighb_idx[idx]])
             connection_sides_idx.append(current_closest_direction)
             connection_sides_idx.append((current_closest_direction + 2) % 4)
             city_orientations.append(current_closest_direction)