# garage.sampler.local_sampler¶

Sampler that runs workers in the main process.

class LocalSampler(worker_factory, agents, envs)[source]

Sampler that runs workers in the main process.

This is probably the simplest possible sampler. It’s called the “Local” sampler because it runs everything in the same process and thread as where it was called from.

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 sample 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.

classmethod from_worker_factory(cls, worker_factory, agents, envs)[source]

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 (Agent or List[Agent]) – Agent(s) to use to sample 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

obtain_samples(self, itr, num_samples, agent_update, env_update=None)[source]

Collect at least a given number transitions (timesteps).

Parameters
• itr (int) – The current iteration number. Using this argument is deprecated.

• num_samples (int) – Minimum number of transitions / timesteps 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

obtain_exact_episodes(self, n_eps_per_worker, agent_update, env_update=None)[source]

Sample an exact number of episodes per worker.

Parameters
• n_eps_per_worker (int) – Exact number of episodes to gather for each worker.

• 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 samplin episodes. If a list is passed in, it must have length exactly factory.n_workers, and will be spread across the workers.

Returns

Batch of gathered episodes. Always in worker

order. In other words, first all episodes from worker 0, then all episodes from worker 1, etc.

Return type

EpisodeBatch

shutdown_worker(self)[source]

Shutdown the workers.

start_worker(self)

Initialize the sampler.

i.e. launching parallel workers if necessary.