from typing import Any, Callable, Dict, Optional, Union
import numpy as np
from tianshou.data import Collector
from tianshou.policy import BasePolicy
from tianshou.trainer.base import BaseTrainer
from tianshou.utils import BaseLogger, LazyLogger
[docs]class OffpolicyTrainer(BaseTrainer):
"""Create an iterator wrapper for off-policy training procedure.
:param policy: an instance of the :class:`~tianshou.policy.BasePolicy` class.
:param Collector train_collector: the collector used for training.
: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 step_per_epoch: the number of transitions collected per epoch.
:param int step_per_collect: the number of transitions the collector would
collect before the network update, i.e., trainer will collect
"step_per_collect" transitions and do some policy network update repeatedly
in each 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 int/float update_per_step: the number of times the policy network would
be updated per transition after (step_per_collect) transitions are
collected, e.g., if update_per_step set to 0.3, and step_per_collect is 256
, policy will be updated round(256 * 0.3 = 76.8) = 77 times after 256
transitions are collected by the collector. Default to 1.
:param function train_fn: a hook called at the beginning of training 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 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.
:param bool resume_from_log: resume env_step/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
training/testing/updating. 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.
:param bool test_in_train: whether to test in the training phase.
Default to True.
"""
__doc__ = BaseTrainer.gen_doc("offpolicy") + "\n".join(__doc__.split("\n")[1:])
def __init__(
self,
policy: BasePolicy,
train_collector: Collector,
test_collector: Optional[Collector],
max_epoch: int,
step_per_epoch: int,
step_per_collect: int,
episode_per_test: int,
batch_size: int,
update_per_step: Union[int, float] = 1,
train_fn: Optional[Callable[[int, int], None]] = None,
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,
test_in_train: bool = True,
**kwargs: Any,
):
super().__init__(
learning_type="offpolicy",
policy=policy,
train_collector=train_collector,
test_collector=test_collector,
max_epoch=max_epoch,
step_per_epoch=step_per_epoch,
step_per_collect=step_per_collect,
episode_per_test=episode_per_test,
batch_size=batch_size,
update_per_step=update_per_step,
train_fn=train_fn,
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,
test_in_train=test_in_train,
**kwargs,
)
[docs] def policy_update_fn(self, data: Dict[str, Any], result: Dict[str, Any]) -> None:
"""Perform off-policy updates."""
assert self.train_collector is not None
for _ in range(round(self.update_per_step * result["n/st"])):
self.gradient_step += 1
losses = self.policy.update(self.batch_size, self.train_collector.buffer)
self.log_update_data(data, losses)
[docs]def offpolicy_trainer(*args, **kwargs) -> Dict[str, Union[float, str]]: # type: ignore
"""Wrapper for OffPolicyTrainer run method.
It is identical to ``OffpolicyTrainer(...).run()``.
:return: See :func:`~tianshou.trainer.gather_info`.
"""
return OffpolicyTrainer(*args, **kwargs).run()
offpolicy_trainer_iter = OffpolicyTrainer