added init call

examples/shields/rl/15_train_eval_tune.py

@@ -1,6 +1,7 @@
 import gymnasium as gym
 import minigrid
 
+import ray
 from ray.tune import register_env
 from ray import tune, air
 from ray.rllib.algorithms.ppo import PPOConfig
@@ -82,7 +83,6 @@ def ppo(args):
                            metric="episode_reward_mean",
                            mode="max",
                            num_samples=1,
-                           
                        ),
                         run_config=air.RunConfig(
                                 stop = {"episode_reward_mean": 94,
@@ -133,6 +133,7 @@ def ppo(args):
         
     
 def main():
+    ray.init(num_cpus=4)
     import argparse
     args = parse_arguments(argparse)