from typing import Any, Callable, Dict, Optional, Union
import numpy as np
from tianshou.data import Collector, ReplayBuffer
from tianshou.policy import BasePolicy
from tianshou.trainer.base import BaseTrainer
from tianshou.utils import BaseLogger, LazyLogger
[docs]class OfflineTrainer(BaseTrainer):
"""Create an iterator class for offline training procedure.
:param policy: an instance of the :class:`~tianshou.policy.BasePolicy` class.
:param buffer: an instance of the :class:`~tianshou.data.ReplayBuffer` class.
This buffer must be populated with experiences for offline RL.
:param Collector test_collector: the collector used for testing. If it's None,
then no testing will be performed.
:param int max_epoch: the maximum number of epochs for training. The training
process might be finished before reaching ``max_epoch`` if ``stop_fn`` is
set.
:param int update_per_epoch: the number of policy network updates, so-called
gradient steps, per epoch.
:param episode_per_test: the number of episodes for one policy evaluation.
:param int batch_size: the batch size of sample data, which is going to feed in
the policy network.
:param function test_fn: a hook called at the beginning of testing in each
epoch.
It can be used to perform custom additional operations, with the signature
``f(num_epoch: int, step_idx: int) -> None``.
:param function save_best_fn: a hook called when the undiscounted average mean
reward in evaluation phase gets better, with the signature
``f(policy: BasePolicy) -> None``. It was ``save_fn`` previously.
:param function save_checkpoint_fn: a function to save training process and
return the saved checkpoint path, with the signature ``f(epoch: int,
env_step: int, gradient_step: int) -> str``; you can save whatever you want.
Because offline-RL doesn't have env_step, the env_step is always 0 here.
:param bool resume_from_log: resume gradient_step and other metadata from
existing tensorboard log. Default to False.
:param function stop_fn: a function with signature ``f(mean_rewards: float) ->
bool``, receives the average undiscounted returns of the testing result,
returns a boolean which indicates whether reaching the goal.
:param function reward_metric: a function with signature ``f(rewards:
np.ndarray with shape (num_episode, agent_num)) -> np.ndarray with shape
(num_episode,)``, used in multi-agent RL. We need to return a single scalar
for each episode's result to monitor training in the multi-agent RL
setting. This function specifies what is the desired metric, e.g., the
reward of agent 1 or the average reward over all agents.
:param BaseLogger logger: A logger that logs statistics during
updating/testing. Default to a logger that doesn't log anything.
:param bool verbose: whether to print the information. Default to True.
:param bool show_progress: whether to display a progress bar when training.
Default to True.
"""
__doc__ = BaseTrainer.gen_doc("offline") + "\n".join(__doc__.split("\n")[1:])
def __init__(
self,
policy: BasePolicy,
buffer: ReplayBuffer,
test_collector: Optional[Collector],
max_epoch: int,
update_per_epoch: int,
episode_per_test: int,
batch_size: int,
test_fn: Optional[Callable[[int, Optional[int]], None]] = None,
stop_fn: Optional[Callable[[float], bool]] = None,
save_best_fn: Optional[Callable[[BasePolicy], None]] = None,
save_checkpoint_fn: Optional[Callable[[int, int, int], str]] = None,
resume_from_log: bool = False,
reward_metric: Optional[Callable[[np.ndarray], np.ndarray]] = None,
logger: BaseLogger = LazyLogger(),
verbose: bool = True,
show_progress: bool = True,
**kwargs: Any,
):
super().__init__(
learning_type="offline",
policy=policy,
buffer=buffer,
test_collector=test_collector,
max_epoch=max_epoch,
update_per_epoch=update_per_epoch,
step_per_epoch=update_per_epoch,
episode_per_test=episode_per_test,
batch_size=batch_size,
test_fn=test_fn,
stop_fn=stop_fn,
save_best_fn=save_best_fn,
save_checkpoint_fn=save_checkpoint_fn,
resume_from_log=resume_from_log,
reward_metric=reward_metric,
logger=logger,
verbose=verbose,
show_progress=show_progress,
**kwargs,
)
[docs] def policy_update_fn(
self, data: Dict[str, Any], result: Optional[Dict[str, Any]] = None
) -> None:
"""Perform one off-line policy update."""
assert self.buffer
self.gradient_step += 1
losses = self.policy.update(self.batch_size, self.buffer)
data.update({"gradient_step": str(self.gradient_step)})
self.log_update_data(data, losses)
[docs]def offline_trainer(*args, **kwargs) -> Dict[str, Union[float, str]]: # type: ignore
"""Wrapper for offline_trainer run method.
It is identical to ``OfflineTrainer(...).run()``.
:return: See :func:`~tianshou.trainer.gather_info`.
"""
return OfflineTrainer(*args, **kwargs).run()
offline_trainer_iter = OfflineTrainer