issue with boarder resolved

examples/flatland_2_0_example.py

@@ -30,7 +30,7 @@ speed_ration_map = {1.: 0.25,  # Fast passenger train
 
 env = RailEnv(width=50,
               height=50,
-              rail_generator=sparse_rail_generator(num_cities=9,  # 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=0,  # Random seed
                                                    grid_mode=False,
                                                    max_inter_city_rails=2,

flatland/envs/rail_generators.py

@@ -551,7 +551,7 @@ def sparse_rail_generator(num_cities=5, grid_mode=False, max_inter_city_rails=4,
         rail_array = grid_map.grid
         rail_array.fill(0)
         np.random.seed(seed + num_resets)
-        node_radius = int(max_tracks_in_city / 2) + 1
+        node_radius = int(np.ceil(max_tracks_in_city / 2))
         max_inter_city_rails_allowed = max_inter_city_rails
         if max_inter_city_rails_allowed > max_tracks_in_city:
             max_inter_city_rails_allowed = max_tracks_in_city