def learner(
self,
replay: reverb.Client,
counter: counting.Counter,
):
"""The Learning part of the agent."""
act_spec = self._environment_spec.actions
obs_spec = self._environment_spec.observations
# Create online and target networks.
online_networks = self._network_factory(act_spec)
target_networks = self._network_factory(act_spec)
# Make sure observation networks are Sonnet Modules.
observation_network = online_networks.get('observation', tf.identity)
observation_network = tf2_utils.to_sonnet_module(observation_network)
online_networks['observation'] = observation_network
target_observation_network = target_networks.get(
'observation', tf.identity)
target_observation_network = tf2_utils.to_sonnet_module(
target_observation_network)
target_networks['observation'] = target_observation_network
# Get embedding spec and create observation network variables.
emb_spec = tf2_utils.create_variables(observation_network, [obs_spec])
tf2_utils.create_variables(online_networks['policy'], [emb_spec])
tf2_utils.create_variables(online_networks['critic'],
[emb_spec, act_spec])
tf2_utils.create_variables(target_networks['observation'], [obs_spec])
tf2_utils.create_variables(target_networks['policy'], [emb_spec])
tf2_utils.create_variables(target_networks['critic'],
[emb_spec, act_spec])
# The dataset object to learn from.
dataset = datasets.make_reverb_dataset(
server_address=replay.server_address)
dataset = dataset.batch(self._batch_size, drop_remainder=True)
dataset = dataset.prefetch(self._prefetch_size)
# Create a counter and logger for bookkeeping steps and performance.
counter = counting.Counter(counter, 'learner')
logger = loggers.make_default_logger('learner',
time_delta=self._log_every,
steps_key='learner_steps')
# Create policy loss module if a factory is passed.
if self._policy_loss_factory:
policy_loss_module = self._policy_loss_factory()
else:
policy_loss_module = None
# Return the learning agent.
return learning.MPOLearner(
policy_network=online_networks['policy'],
critic_network=online_networks['critic'],
observation_network=observation_network,
target_policy_network=target_networks['policy'],
target_critic_network=target_networks['critic'],
target_observation_network=target_observation_network,
discount=self._additional_discount,
num_samples=self._num_samples,
target_policy_update_period=self._target_policy_update_period,
target_critic_update_period=self._target_critic_update_period,
policy_loss_module=policy_loss_module,
dataset=dataset,
counter=counter,
logger=logger)
def __init__(
self,
environment_spec: specs.EnvironmentSpec,
policy_network: snt.Module,
critic_network: snt.Module,
observation_network: types.TensorTransformation = tf.identity,
discount: float = 0.99,
batch_size: int = 256,
prefetch_size: int = 4,
target_policy_update_period: int = 100,
target_critic_update_period: int = 100,
min_replay_size: int = 1000,
max_replay_size: int = 1000000,
samples_per_insert: float = 32.0,
policy_loss_module: snt.Module = None,
policy_optimizer: snt.Optimizer = None,
critic_optimizer: snt.Optimizer = None,
n_step: int = 5,
num_samples: int = 20,
clipping: bool = True,
logger: loggers.Logger = None,
counter: counting.Counter = None,
checkpoint: bool = True,
replay_table_name: str = adders.DEFAULT_PRIORITY_TABLE,
):
"""Initialize the agent.
Args:
environment_spec: description of the actions, observations, etc.
policy_network: the online (optimized) policy.
critic_network: the online critic.
observation_network: optional network to transform the observations before
they are fed into any network.
discount: discount to use for TD updates.
batch_size: batch size for updates.
prefetch_size: size to prefetch from replay.
target_policy_update_period: number of updates to perform before updating
the target policy network.
target_critic_update_period: number of updates to perform before updating
the target critic network.
min_replay_size: minimum replay size before updating.
max_replay_size: maximum replay size.
samples_per_insert: number of samples to take from replay for every insert
that is made.
policy_loss_module: configured MPO loss function for the policy
optimization; defaults to sensible values on the control suite.
See `acme/tf/losses/mpo.py` for more details.
policy_optimizer: optimizer to be used on the policy.
critic_optimizer: optimizer to be used on the critic.
n_step: number of steps to squash into a single transition.
num_samples: number of actions to sample when doing a Monte Carlo
integration with respect to the policy.
clipping: whether to clip gradients by global norm.
logger: logging object used to write to logs.
counter: counter object used to keep track of steps.
checkpoint: boolean indicating whether to checkpoint the learner.
replay_table_name: string indicating what name to give the replay table.
"""
# Create a replay server to add data to.
replay_table = reverb.Table(
name=adders.DEFAULT_PRIORITY_TABLE,
sampler=reverb.selectors.Uniform(),
remover=reverb.selectors.Fifo(),
max_size=max_replay_size,
rate_limiter=reverb.rate_limiters.MinSize(min_size_to_sample=1),
signature=adders.NStepTransitionAdder.signature(environment_spec))
self._server = reverb.Server([replay_table], port=None)
# The adder is used to insert observations into replay.
address = f'localhost:{self._server.port}'
adder = adders.NStepTransitionAdder(client=reverb.Client(address),
n_step=n_step,
discount=discount)
# The dataset object to learn from.
dataset = datasets.make_reverb_dataset(
table=replay_table_name,
client=reverb.TFClient(address),
batch_size=batch_size,
prefetch_size=prefetch_size,
environment_spec=environment_spec,
transition_adder=True)
# Make sure observation network is a Sonnet Module.
observation_network = tf2_utils.to_sonnet_module(observation_network)
# Create target networks before creating online/target network variables.
target_policy_network = copy.deepcopy(policy_network)
target_critic_network = copy.deepcopy(critic_network)
target_observation_network = copy.deepcopy(observation_network)
# Get observation and action specs.
act_spec = environment_spec.actions
obs_spec = environment_spec.observations
emb_spec = tf2_utils.create_variables(observation_network, [obs_spec])
# Create the behavior policy.
behavior_network = snt.Sequential([
observation_network,
policy_network,
networks.StochasticSamplingHead(),
])
# Create variables.
tf2_utils.create_variables(policy_network, [emb_spec])
tf2_utils.create_variables(critic_network, [emb_spec, act_spec])
tf2_utils.create_variables(target_policy_network, [emb_spec])
tf2_utils.create_variables(target_critic_network, [emb_spec, act_spec])
tf2_utils.create_variables(target_observation_network, [obs_spec])
# Create the actor which defines how we take actions.
actor = actors.FeedForwardActor(policy_network=behavior_network,
adder=adder)
# Create optimizers.
policy_optimizer = policy_optimizer or snt.optimizers.Adam(1e-4)
critic_optimizer = critic_optimizer or snt.optimizers.Adam(1e-4)
# The learner updates the parameters (and initializes them).
learner = learning.MPOLearner(
policy_network=policy_network,
critic_network=critic_network,
observation_network=observation_network,
target_policy_network=target_policy_network,
target_critic_network=target_critic_network,
target_observation_network=target_observation_network,
policy_loss_module=policy_loss_module,
policy_optimizer=policy_optimizer,
critic_optimizer=critic_optimizer,
clipping=clipping,
discount=discount,
num_samples=num_samples,
target_policy_update_period=target_policy_update_period,
target_critic_update_period=target_critic_update_period,
dataset=dataset,
logger=logger,
counter=counter,
checkpoint=checkpoint)
super().__init__(actor=actor,
learner=learner,
min_observations=max(batch_size, min_replay_size),
observations_per_step=float(batch_size) /
samples_per_insert)