Collector no longer has preprocess_fn

[destin-v]

In the latest update to Tianshou 1.1.0 it looks like the preprocess_fn from Collector has been removed. I was using it to record full episode rollouts and running some analysis on them. Now that preprocess_fn has been removed, is there a better way to get the obs, rew, terminated, truncated, info?

[Trinkle23897]

I think after #1196 you can set on_episode_done_hook or on_step_hook in Collector to achieve this.

[MischaPanch]

Hi @destin-v . It was removed a long time ago, I think (probably as part of 1.0.0) since it was unused in the codebase and increased the complexity of the already very complicated Collector.

Just now we have finished work on extending the Collector with hooks, it's already merged on master. I'm about to merge some internal improvements in #1214 , which however don't affect the public interfaces.

There's now a dedicated mechanism for processing batches at step and at episode completion by passing hooks to the collector. Have a look at the docstrings and examples there pls. We will add more documentation and tutorials on these new features with the next release.

So for your experiments, I suggest you move to the version currently on master

[MischaPanch]

As a benefit, the internals of Collector are now much more documented

[destin-v]

Okay, sounds good. I would recommend that the Cheat Sheet remove the documentation for preprocess_fn since it does not exist anymore. We will likely want some documentation on on_episode_done_hook and on_step_hook.

[MischaPanch]

Documentation is generally severely lacking.. I am planning to devote a lot of time for it in September

[MischaPanch]

Feel free to start on that if you want to and have time! If that's the case, let's have a short call to coordinate