updated the way connected directions are chosen.

examples/flatland_2_0_example.py

@@ -39,7 +39,7 @@ env = RailEnv(width=50,
                                                    seed=15,  # Random seed
                                                    grid_mode=False,
                                                    max_connection_points_per_side=2,
-                                                   max_nr_connection_directions=4,
+                                                   max_nr_connection_directions=2,
                                                    ),
               schedule_generator=sparse_schedule_generator(),
               number_of_agents=50,

flatland/envs/rail_generators.py

@@ -701,13 +701,11 @@ def sparse_rail_generator(num_cities=5, num_trainstations=2, min_node_dist=20, n
             # TODO: Change the way this code works! Check that we get sufficient direction.
             # TODO: Check if this works as expected
             while len(connection_sides_idx) < max_nr_connection_directions and idx < len(neighb_dist):
-                if closest_direction(node_position,
-                                     node_positions[closest_neighb_idx[idx]]) not in connection_sides_idx:
-                    connection_sides_idx.append(
-                        closest_direction(node_position, node_positions[closest_neighb_idx[idx]]))
-                    idx += 1
-                else:
-                    idx += 1
+                current_closest_direction = closest_direction(node_position, node_positions[closest_neighb_idx[idx]])
+                if current_closest_direction not in connection_sides_idx:
+                    connection_sides_idx.append(current_closest_direction)
+                idx += 1
+
 
             # set the number of connection points for each direction
             connections_per_direction = np.zeros(4, dtype=int)