garage.sampler.sampler

Base sampler class.

class Sampler(algo, env)

Bases: abc.ABC

Abstract base class of all samplers.

Implementations of this class should override construct, obtain_samples, and shutdown_worker. construct takes a WorkerFactory, which implements most of the RL-specific functionality a Sampler needs. Specifically, it specifies how to construct `Worker`s, which know how to collect episodes and update both agents and environments.

Currently, __init__ is also part of the interface, but calling it is deprecated. start_worker is also deprecated, and does not need to be implemented.

classmethod from_worker_factory(cls, worker_factory, agents, envs)

Construct this sampler.

Parameters:

• worker_factory (WorkerFactory) – Pickleable factory for creating workers. Should be transmitted to other processes / nodes where work needs to be done, then workers should be constructed there.
• agents (Policy or List[Policy]) – Agent(s) to use to collect episodes. If a list is passed in, it must have length exactly worker_factory.n_workers, and will be spread across the workers.
• envs (Environment or List[Environment]) – Environment from which episodes are sampled. If a list is passed in, it must have length exactly worker_factory.n_workers, and will be spread across the workers.

Returns:

An instance of cls.

Return type:

Sampler

start_worker(self)

Initialize the sampler.

i.e. launching parallel workers if necessary.

This method is deprecated, please launch workers in construct instead.

obtain_samples(self, itr, num_samples, agent_update, env_update=None)

Collect at least a given number transitions :class:`TimeStep`s.

Parameters:

• itr (int) – The current iteration number. Using this argument is deprecated.
• num_samples (int) – Minimum number of :class:`TimeStep`s to sample.
• agent_update (object) – Value which will be passed into the agent_update_fn before sampling episodes. If a list is passed in, it must have length exactly factory.n_workers, and will be spread across the workers.
• env_update (object) – Value which will be passed into the env_update_fn before sampling episodes. If a list is passed in, it must have length exactly factory.n_workers, and will be spread across the workers.

Returns:

The batch of collected episodes.

Return type:

EpisodeBatch

shutdown_worker(self)

Terminate workers if necessary.

Because Python object destruction can be somewhat unpredictable, this method isn’t deprecated.