fix convergence issue

flatland/envs/schedule_generators.py

@@ -164,14 +164,14 @@ def random_schedule_generator(speed_ratio_map: Mapping[float, float] = None) ->
             return [], [], [], []
 
         if len(valid_positions) < num_agents:
-            warnings("schedule_generators: len(valid_positions) < num_agents")
+            warnings.warn("schedule_generators: len(valid_positions) < num_agents")
             return [], [], [], []
 
         agents_position_idx = [i for i in np.random.choice(len(valid_positions), num_agents, replace=False)]
         agents_position = [valid_positions[agents_position_idx[i]] for i in range(num_agents)]
         agents_target_idx = [i for i in np.random.choice(len(valid_positions), num_agents, replace=False)]
         agents_target = [valid_positions[agents_target_idx[i]] for i in range(num_agents)]
-        update_agents = np.ones(num_agents)
+        update_agents = np.zeros(num_agents)
 
         re_generate = True
         cnt = 0
@@ -180,12 +180,10 @@ def random_schedule_generator(speed_ratio_map: Mapping[float, float] = None) ->
             # update position
             for i in range(num_agents):
                 if update_agents[i] == 1:
-                    x = np.arange(len(valid_positions))
-                    x = np.setdiff1d(x,agents_position_idx)
+                    x = np.setdiff1d(np.arange(len(valid_positions)), agents_position_idx)
                     agents_position_idx[i] = np.random.choice(x)
                     agents_position[i] = valid_positions[agents_position_idx[i]]
-                    x = np.arange(len(valid_positions))
-                    x = np.setdiff1d(x,agents_target_idx)
+                    x = np.setdiff1d(np.arange(len(valid_positions)), agents_target_idx)
                     agents_target_idx[i] = np.random.choice(x)
                     agents_target[i] = valid_positions[agents_target_idx[i]]
             update_agents = np.zeros(num_agents)
@@ -212,8 +210,6 @@ def random_schedule_generator(speed_ratio_map: Mapping[float, float] = None) ->
 
                 if len(valid_starting_directions) == 0:
                     re_generate = True
-                    print("agent:", i, new_position)
-                    print("invalid")
                     update_agents[i] = 1
                     break
                 else: