base

Source code: tianshou/trainer/base.py

---

class BaseTrainer(policy: ~tianshou.policy.base.BasePolicy, max_epoch: int, batch_size: int | None, train_collector: ~tianshou.data.collector.Collector | None = None, test_collector: ~tianshou.data.collector.Collector | None = None, buffer: ~tianshou.data.buffer.base.ReplayBuffer | None = None, step_per_epoch: int | None = None, repeat_per_collect: int | None = None, episode_per_test: int | None = None, update_per_step: float = 1.0, step_per_collect: int | None = None, episode_per_collect: int | None = None, train_fn: ~collections.abc.Callable[[int, int], None] | None = None, test_fn: ~collections.abc.Callable[[int, int | None], None] | None = None, stop_fn: ~collections.abc.Callable[[float], bool] | None = None, save_best_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None, save_checkpoint_fn: ~collections.abc.Callable[[int, int, int], str] | None = None, resume_from_log: bool = False, reward_metric: ~collections.abc.Callable[[~numpy.ndarray], ~numpy.ndarray] | None = None, logger: ~tianshou.utils.logger.base.BaseLogger = <tianshou.utils.logger.base.LazyLogger object>, verbose: bool = True, show_progress: bool = True, test_in_train: bool = True, save_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None)

An iterator base class for trainers.

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

Parameters:

• policy – an instance of the BasePolicy class.

• batch_size – the batch size of sample data, which is going to feed in the policy network. If None, will use the whole buffer in each gradient step.

• train_collector – the collector used for training.

• test_collector – the collector used for testing. If it’s None, then no testing will be performed.

• buffer – the replay buffer used for off-policy algorithms or for pre-training. If a policy overrides the process_buffer method, the replay buffer will be pre-processed before training.

• max_epoch – the maximum number of epochs for training. The training process might be finished before reaching max_epoch if stop_fn is set.

• step_per_epoch – the number of transitions collected per epoch.

• repeat_per_collect – the number of repeat time for policy learning, for example, set it to 2 means the policy needs to learn each given batch data twice. Only used in on-policy algorithms

• episode_per_test – the number of episodes for one policy evaluation.

• update_per_step – only used in off-policy algorithms. How many gradient steps to perform per step in the environment (i.e., per sample added to the buffer).

• 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.

• episode_per_collect – the number of episodes the collector would collect before the network update, i.e., trainer will collect “episode_per_collect” episodes and do some policy network update repeatedly in each epoch.

• 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.

• 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.

• 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.

• 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.

• resume_from_log – resume env_step/gradient_step and other metadata from existing tensorboard log.

• 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.

• 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.

• logger – A logger that logs statistics during training/testing/updating. To not log anything, keep the default logger.

• verbose – whether to print status information to stdout. If set to False, status information will still be logged (provided that logging is enabled via the logging module).

• show_progress – whether to display a progress bar when training.

• test_in_train – whether to test in the training phase.

static gen_doc(learning_type: str) → str

Document string for subclass trainer.

abstract policy_update_fn(collect_stats: CollectStatsBase) → TrainingStats

Policy update function for different trainer implementation.

Parameters:

collect_stats – provides info about the most recent collection. In the offline case, this will contain stats of the whole dataset

reset() → None

Initialize or reset the instance to yield a new iterator from zero.

run() → InfoStats

Consume iterator.

See itertools - recipes. Use functions that consume iterators at C speed (feed the entire iterator into a zero-length deque).

test_step() → tuple[CollectStats, bool]

Perform one testing step.

train_step() → tuple[CollectStats, bool]

Perform one training step.

If test_in_train and stop_fn are set, will compute the stop_fn on the mean return of the training data. Then, if the stop_fn is True there, will collect test data also compute the stop_fn of the mean return on it. Finally, if the latter is also True, will set should_stop_training to True.

Returns:

A tuple of the training stats and a boolean indicating whether to stop training.

class OfflineTrainer(policy: ~tianshou.policy.base.BasePolicy, max_epoch: int, batch_size: int | None, train_collector: ~tianshou.data.collector.Collector | None = None, test_collector: ~tianshou.data.collector.Collector | None = None, buffer: ~tianshou.data.buffer.base.ReplayBuffer | None = None, step_per_epoch: int | None = None, repeat_per_collect: int | None = None, episode_per_test: int | None = None, update_per_step: float = 1.0, step_per_collect: int | None = None, episode_per_collect: int | None = None, train_fn: ~collections.abc.Callable[[int, int], None] | None = None, test_fn: ~collections.abc.Callable[[int, int | None], None] | None = None, stop_fn: ~collections.abc.Callable[[float], bool] | None = None, save_best_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None, save_checkpoint_fn: ~collections.abc.Callable[[int, int, int], str] | None = None, resume_from_log: bool = False, reward_metric: ~collections.abc.Callable[[~numpy.ndarray], ~numpy.ndarray] | None = None, logger: ~tianshou.utils.logger.base.BaseLogger = <tianshou.utils.logger.base.LazyLogger object>, verbose: bool = True, show_progress: bool = True, test_in_train: bool = True, save_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None)

Offline trainer, samples mini-batches from buffer and passes them to update.

Uses a buffer directly and usually does not have a collector. An iterator class for offline trainer procedure.

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

The “step” in offline trainer means a gradient step.

Example usage:

trainer = OfflineTrainer(...)
for epoch, epoch_stat, info in trainer:
    print("Epoch:", epoch)
    print(epoch_stat)
    print(info)
    do_something_with_policy()
    query_something_about_policy()
    make_a_plot_with(epoch_stat)
    display(info)

• epoch int: the epoch number

• epoch_stat dict: a large collection of metrics of the current epoch

• info dict: result returned from gather_info()

You can even iterate on several trainers at the same time:

trainer1 = OfflineTrainer(...)
trainer2 = OfflineTrainer(...)
for result1, result2, ... in zip(trainer1, trainer2, ...):
    compare_results(result1, result2, ...)

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

Parameters:

• policy – an instance of the BasePolicy class.

• batch_size – the batch size of sample data, which is going to feed in the policy network. If None, will use the whole buffer in each gradient step.

• train_collector – the collector used for training.

• test_collector – the collector used for testing. If it’s None, then no testing will be performed.

• buffer – the replay buffer used for off-policy algorithms or for pre-training. If a policy overrides the process_buffer method, the replay buffer will be pre-processed before training.

• max_epoch – the maximum number of epochs for training. The training process might be finished before reaching max_epoch if stop_fn is set.

• step_per_epoch – the number of transitions collected per epoch.

• repeat_per_collect – the number of repeat time for policy learning, for example, set it to 2 means the policy needs to learn each given batch data twice. Only used in on-policy algorithms

• episode_per_test – the number of episodes for one policy evaluation.

• update_per_step – only used in off-policy algorithms. How many gradient steps to perform per step in the environment (i.e., per sample added to the buffer).

• 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.

• episode_per_collect – the number of episodes the collector would collect before the network update, i.e., trainer will collect “episode_per_collect” episodes and do some policy network update repeatedly in each epoch.

• 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.

• 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.

• 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.

• 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.

• resume_from_log – resume env_step/gradient_step and other metadata from existing tensorboard log.

• 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.

• 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.

• logger – A logger that logs statistics during training/testing/updating. To not log anything, keep the default logger.

• verbose – whether to print status information to stdout. If set to False, status information will still be logged (provided that logging is enabled via the logging module).

• show_progress – whether to display a progress bar when training.

• test_in_train – whether to test in the training phase.

policy_update_fn(collect_stats: CollectStatsBase | None = None) → TrainingStats

Perform one off-line policy update.

class OffpolicyTrainer(policy: ~tianshou.policy.base.BasePolicy, max_epoch: int, batch_size: int | None, train_collector: ~tianshou.data.collector.Collector | None = None, test_collector: ~tianshou.data.collector.Collector | None = None, buffer: ~tianshou.data.buffer.base.ReplayBuffer | None = None, step_per_epoch: int | None = None, repeat_per_collect: int | None = None, episode_per_test: int | None = None, update_per_step: float = 1.0, step_per_collect: int | None = None, episode_per_collect: int | None = None, train_fn: ~collections.abc.Callable[[int, int], None] | None = None, test_fn: ~collections.abc.Callable[[int, int | None], None] | None = None, stop_fn: ~collections.abc.Callable[[float], bool] | None = None, save_best_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None, save_checkpoint_fn: ~collections.abc.Callable[[int, int, int], str] | None = None, resume_from_log: bool = False, reward_metric: ~collections.abc.Callable[[~numpy.ndarray], ~numpy.ndarray] | None = None, logger: ~tianshou.utils.logger.base.BaseLogger = <tianshou.utils.logger.base.LazyLogger object>, verbose: bool = True, show_progress: bool = True, test_in_train: bool = True, save_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None)

Offpolicy trainer, samples mini-batches from buffer and passes them to update.

Note that with this trainer, it is expected that the policy’s learn method does not perform additional mini-batching but just updates params from the received mini-batch. An iterator class for offpolicy trainer procedure.

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

The “step” in offpolicy trainer means an environment step (a.k.a. transition).

Example usage:

trainer = OffpolicyTrainer(...)
for epoch, epoch_stat, info in trainer:
    print("Epoch:", epoch)
    print(epoch_stat)
    print(info)
    do_something_with_policy()
    query_something_about_policy()
    make_a_plot_with(epoch_stat)
    display(info)

• epoch int: the epoch number

• epoch_stat dict: a large collection of metrics of the current epoch

• info dict: result returned from gather_info()

You can even iterate on several trainers at the same time:

trainer1 = OffpolicyTrainer(...)
trainer2 = OffpolicyTrainer(...)
for result1, result2, ... in zip(trainer1, trainer2, ...):
    compare_results(result1, result2, ...)

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

Parameters:

• policy – an instance of the BasePolicy class.

• batch_size – the batch size of sample data, which is going to feed in the policy network. If None, will use the whole buffer in each gradient step.

• train_collector – the collector used for training.

• test_collector – the collector used for testing. If it’s None, then no testing will be performed.

• buffer – the replay buffer used for off-policy algorithms or for pre-training. If a policy overrides the process_buffer method, the replay buffer will be pre-processed before training.

• max_epoch – the maximum number of epochs for training. The training process might be finished before reaching max_epoch if stop_fn is set.

• step_per_epoch – the number of transitions collected per epoch.

• repeat_per_collect – the number of repeat time for policy learning, for example, set it to 2 means the policy needs to learn each given batch data twice. Only used in on-policy algorithms

• episode_per_test – the number of episodes for one policy evaluation.

• update_per_step – only used in off-policy algorithms. How many gradient steps to perform per step in the environment (i.e., per sample added to the buffer).

• 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.

• episode_per_collect – the number of episodes the collector would collect before the network update, i.e., trainer will collect “episode_per_collect” episodes and do some policy network update repeatedly in each epoch.

• 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.

• 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.

• 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.

• 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.

• resume_from_log – resume env_step/gradient_step and other metadata from existing tensorboard log.

• 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.

• 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.

• logger – A logger that logs statistics during training/testing/updating. To not log anything, keep the default logger.

• verbose – whether to print status information to stdout. If set to False, status information will still be logged (provided that logging is enabled via the logging module).

• show_progress – whether to display a progress bar when training.

• test_in_train – whether to test in the training phase.

policy_update_fn(collect_stats: CollectStatsBase) → TrainingStats

Perform update_per_step * n_collected_steps gradient steps by sampling mini-batches from the buffer.

Parameters:

collect_stats – the TrainingStats instance returned by the last gradient step. Some values in it will be replaced by their moving averages.

class OnpolicyTrainer(policy: ~tianshou.policy.base.BasePolicy, max_epoch: int, batch_size: int | None, train_collector: ~tianshou.data.collector.Collector | None = None, test_collector: ~tianshou.data.collector.Collector | None = None, buffer: ~tianshou.data.buffer.base.ReplayBuffer | None = None, step_per_epoch: int | None = None, repeat_per_collect: int | None = None, episode_per_test: int | None = None, update_per_step: float = 1.0, step_per_collect: int | None = None, episode_per_collect: int | None = None, train_fn: ~collections.abc.Callable[[int, int], None] | None = None, test_fn: ~collections.abc.Callable[[int, int | None], None] | None = None, stop_fn: ~collections.abc.Callable[[float], bool] | None = None, save_best_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None, save_checkpoint_fn: ~collections.abc.Callable[[int, int, int], str] | None = None, resume_from_log: bool = False, reward_metric: ~collections.abc.Callable[[~numpy.ndarray], ~numpy.ndarray] | None = None, logger: ~tianshou.utils.logger.base.BaseLogger = <tianshou.utils.logger.base.LazyLogger object>, verbose: bool = True, show_progress: bool = True, test_in_train: bool = True, save_fn: ~collections.abc.Callable[[~tianshou.policy.base.BasePolicy], None] | None = None)

An iterator class for onpolicy trainer procedure.

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

The “step” in onpolicy trainer means an environment step (a.k.a. transition).

Example usage:

trainer = OnpolicyTrainer(...)
for epoch, epoch_stat, info in trainer:
    print("Epoch:", epoch)
    print(epoch_stat)
    print(info)
    do_something_with_policy()
    query_something_about_policy()
    make_a_plot_with(epoch_stat)
    display(info)

• epoch int: the epoch number

• epoch_stat dict: a large collection of metrics of the current epoch

• info dict: result returned from gather_info()

You can even iterate on several trainers at the same time:

trainer1 = OnpolicyTrainer(...)
trainer2 = OnpolicyTrainer(...)
for result1, result2, ... in zip(trainer1, trainer2, ...):
    compare_results(result1, result2, ...)

Returns an iterator that yields a 3-tuple (epoch, stats, info) of train results on every epoch.

Parameters:

• policy – an instance of the BasePolicy class.

• batch_size – the batch size of sample data, which is going to feed in the policy network. If None, will use the whole buffer in each gradient step.

• train_collector – the collector used for training.

• test_collector – the collector used for testing. If it’s None, then no testing will be performed.

• buffer – the replay buffer used for off-policy algorithms or for pre-training. If a policy overrides the process_buffer method, the replay buffer will be pre-processed before training.

• max_epoch – the maximum number of epochs for training. The training process might be finished before reaching max_epoch if stop_fn is set.

• step_per_epoch – the number of transitions collected per epoch.

• repeat_per_collect – the number of repeat time for policy learning, for example, set it to 2 means the policy needs to learn each given batch data twice. Only used in on-policy algorithms

• episode_per_test – the number of episodes for one policy evaluation.

• update_per_step – only used in off-policy algorithms. How many gradient steps to perform per step in the environment (i.e., per sample added to the buffer).

• 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.

• episode_per_collect – the number of episodes the collector would collect before the network update, i.e., trainer will collect “episode_per_collect” episodes and do some policy network update repeatedly in each epoch.

• 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.

• 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.

• 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.

• 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.

• resume_from_log – resume env_step/gradient_step and other metadata from existing tensorboard log.

• 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.

• 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.

• logger – A logger that logs statistics during training/testing/updating. To not log anything, keep the default logger.

• verbose – whether to print status information to stdout. If set to False, status information will still be logged (provided that logging is enabled via the logging module).

• show_progress – whether to display a progress bar when training.

• test_in_train – whether to test in the training phase.

policy_update_fn(result: CollectStatsBase | None = None) → TrainingStats

Perform one on-policy update by passing the entire buffer to the policy’s update method.