How to monitor the episode/epoch return/length in Tianshou?

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- exception-raising bug
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import tianshou, gymnasium as gym, torch, numpy, sys
print(tianshou.__version__, gym.__version__, torch.__version__, numpy.__version__, sys.version, sys.platform)

I'm using the trainer in Tianshou for MARL, but how can I monitor the episode/epoch return and length in tianshou in the training process?

You should check the collector's return value. It has episodic statistic number. For example:

tianshou/tianshou/data/collector.py

Lines 574 to 581 in 5bf923c

    
           return CollectStats.with_autogenerated_stats( 
        
               returns=np.array(episode_returns), 
        
               lens=np.array(episode_lens), 
        
               n_collected_episodes=num_collected_episodes, 
        
               n_collected_steps=step_count, 
        
               collect_time=collect_time, 
        
               collect_speed=step_count / collect_time, 
        
           )

	return CollectStats.with_autogenerated_stats(
	returns=np.array(episode_returns),
	lens=np.array(episode_lens),
	n_collected_episodes=num_collected_episodes,
	n_collected_steps=step_count,
	collect_time=collect_time,
	collect_speed=step_count / collect_time,
	)