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57 lines
2.3 KiB
ReStructuredText
57 lines
2.3 KiB
ReStructuredText
.. _trainer-reference-docs:
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Trainer API
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===========
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The :py:class:`~ray.rllib.agents.trainer.Trainer` class is the highest-level API in RLlib.
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It allows you to train and evaluate policies, save an experiment's progress and restore from
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a prior saved experiment when continuing an RL run.
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:py:class:`~ray.rllib.agents.trainer.Trainer` is a sub-class
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of :py:class:`~ray.tune.Trainable`
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and thus fully supports distributed hyperparameter tuning for RL.
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.. https://docs.google.com/drawings/d/1J0nfBMZ8cBff34e-nSPJZMM1jKOuUL11zFJm6CmWtJU/edit
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.. figure:: ../images/trainer_class_overview.svg
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:align: left
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**A typical RLlib Trainer object:** The components sitting inside a Trainer are
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normally N :py:class:`~ray.rllib.evaluation.worker_set.WorkerSet`s
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(each consisting of one local :py:class:`~ray.rllib.evaluation.RolloutWorker`
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and zero or more \@ray.remote
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:py:class:`~ray.rllib.evaluation.RolloutWorker`s),
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a set of :py:class:`~ray.rllib.policy.Policy`(ies)
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and their NN models per worker, and a (already vectorized)
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RLlib :py:class:`~ray.rllib.env.base_env.BaseEnv` per worker.
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Building Custom Trainer Classes
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-------------------------------
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.. warning::
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As of Ray >= 1.9, it is no longer recommended to use the `build_trainer()` utility
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function for creating custom Trainer sub-classes.
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Instead, follow the simple guidelines here for directly sub-classing from
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:py:class:`~ray.rllib.agents.trainer.Trainer`.
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In order to create a custom Trainer, sub-class the
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:py:class:`~ray.rllib.agents.trainer.Trainer` class
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and override one or more of its methods. Those are in particular:
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* :py:meth:`~ray.rllib.agents.trainer.Trainer.get_default_config`
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* :py:meth:`~ray.rllib.agents.trainer.Trainer.validate_config`
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* :py:meth:`~ray.rllib.agents.trainer.Trainer.get_default_policy_class`
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* :py:meth:`~ray.rllib.agents.trainer.Trainer.setup`
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* :py:meth:`~ray.rllib.agents.trainer.Trainer.step_attempt`
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* :py:meth:`~ray.rllib.agents.trainer.Trainer.execution_plan`
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`See here for an example on how to override Trainer <https://github.com/ray-project/ray/blob/master/rllib/algorithms/pg/pg.py>`_.
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Trainer base class (ray.rllib.agents.trainer.Trainer)
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-----------------------------------------------------
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.. autoclass:: ray.rllib.agents.trainer.Trainer
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:special-members: __init__
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:members:
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.. static-members: get_default_config, execution_plan
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