def update(self, rollouts: Sequence[StepSequence], use_empirical_returns: bool = False):
"""
Adapt the parameters of the advantage function estimator, minimizing the MSE loss for the given samples.
:param rollouts: batch of rollouts
:param use_empirical_returns: use the return from the rollout (True) or the ones from the V-fcn (False)
:return adv: tensor of advantages after V-function updates
"""
# Turn the batch of rollouts into a list of steps
concat_ros = StepSequence.concat(rollouts)
concat_ros.torch(data_type=to.get_default_dtype())
if use_empirical_returns:
# Compute the value targets (empirical discounted returns) for all samples
v_targ = discounted_values(rollouts, self.gamma).view(-1, 1)
else:
# Use the value function to compute the value targets (also called bootstrapping)
v_targ = self.tdlamda_returns(concat_ros=concat_ros)
concat_ros.add_data('v_targ', v_targ)
# Logging
with to.no_grad():
v_pred_old = self.values(concat_ros)
loss_old = self.loss_fcn(v_pred_old, v_targ)
vfcn_grad_norm = []
# Iterate over all gathered samples num_epoch times
for e in range(self.num_epoch):
for batch in tqdm(concat_ros.split_shuffled_batches(
self.batch_size, complete_rollouts=isinstance(self.vfcn, RecurrentPolicy)),
total=num_iter_from_rollouts(None, concat_ros, self.batch_size),
desc=f'Epoch {e}', unit='batches', file=sys.stdout, leave=False):
# Reset the gradients
self.optim.zero_grad()
# Make predictions for this mini-batch using values function
v_pred = self.values(batch)
# Compute estimator loss for this mini-batch and backpropagate
vfcn_loss = self.loss_fcn(v_pred, batch.v_targ)
vfcn_loss.backward()
# Clip the gradients if desired
vfcn_grad_norm.append(Algorithm.clip_grad(self.vfcn, self.max_grad_norm))
# Call optimizer
self.optim.step()
# Update the learning rate if a scheduler has been specified
if self._lr_scheduler is not None:
self._lr_scheduler.step()
# Estimate the advantage after fitting the parameters of the V-fcn
adv = self.gae(concat_ros) # is done with to.no_grad()
with to.no_grad():
v_pred_new = self.values(concat_ros)
loss_new = self.loss_fcn(v_pred_new, v_targ)
vfcn_loss_impr = loss_old - loss_new # positive values are desired
explvar = explained_var(v_pred_new, v_targ) # values close to 1 are desired
# Log metrics computed from the old value function (before the update)
self.logger.add_value('explained var critic', explvar, 4)
self.logger.add_value('loss improv critic', vfcn_loss_impr, 4)
self.logger.add_value('avg grad norm critic', np.mean(vfcn_grad_norm), 4)
if self._lr_scheduler is not None:
self.logger.add_value('lr critic', self._lr_scheduler.get_last_lr(), 6)
return adv
def update(self, rollouts: Sequence[StepSequence]):
# Turn the batch of rollouts into a list of steps
concat_ros = StepSequence.concat(rollouts)
concat_ros.torch(data_type=to.get_default_dtype())
with to.no_grad():
# Compute the action probabilities using the old (before update) policy
act_stats = compute_action_statistics(concat_ros, self._expl_strat)
log_probs_old = act_stats.log_probs
act_distr_old = act_stats.act_distr
# Compute value predictions using the old old (before update) value function
v_pred_old = self._critic.values(concat_ros)
# Attach advantages and old log probs to rollout
concat_ros.add_data('log_probs_old', log_probs_old)
concat_ros.add_data('v_pred_old', v_pred_old)
# For logging the gradient norms
policy_grad_norm = []
value_fcn_grad_norm = []
# Compute the value targets (empirical discounted returns) for all samples before fitting the V-fcn parameters
adv = self._critic.gae(concat_ros) # done with to.no_grad()
v_targ = discounted_values(rollouts, self._critic.gamma).view(
-1, 1) # empirical discounted returns
concat_ros.add_data('adv', adv)
concat_ros.add_data('v_targ', v_targ)
# Iterations over the whole data set
for e in range(self.num_epoch):
for batch in tqdm(concat_ros.split_shuffled_batches(
self.batch_size,
complete_rollouts=self._policy.is_recurrent
or isinstance(self._critic.value_fcn, RecurrentPolicy)),
total=num_iter_from_rollouts(
None, concat_ros, self.batch_size),
desc=f'Epoch {e}',
unit='batches',
file=sys.stdout,
leave=False):
# Reset the gradients
self.optim.zero_grad()
# Compute log of the action probabilities for the mini-batch
log_probs = compute_action_statistics(
batch, self._expl_strat).log_probs.to(self.policy.device)
# Compute value predictions for the mini-batch
v_pred = self._critic.values(batch)
# Compute combined loss and backpropagate
loss = self.loss_fcn(log_probs, batch.log_probs_old, batch.adv,
v_pred, batch.v_pred_old, batch.v_targ)
loss.backward()
# Clip the gradients if desired
policy_grad_norm.append(
self.clip_grad(self._expl_strat.policy,
self.max_grad_norm))
value_fcn_grad_norm.append(
self.clip_grad(self._critic.value_fcn, self.max_grad_norm))
# Call optimizer
self.optim.step()
if to.isnan(self._expl_strat.noise.std).any():
raise RuntimeError(
f'At least one exploration parameter became NaN! The exploration parameters are'
f'\n{self._expl_strat.std.detach().numpy()}')
# Update the learning rate if a scheduler has been specified
if self._lr_scheduler is not None:
self._lr_scheduler.step()
# Additional logging
if self.log_loss:
with to.no_grad():
# Compute value predictions using the new (after the updates) value function approximator
v_pred = self._critic.values(concat_ros).to(self.policy.device)
v_loss_old = self._critic.loss_fcn(
v_pred_old.to(self.policy.device),
v_targ.to(self.policy.device)).to(self.policy.device)
v_loss_new = self._critic.loss_fcn(v_pred, v_targ).to(
self.policy.device)
value_fcn_loss_impr = v_loss_old - v_loss_new # positive values are desired
# Compute the action probabilities using the new (after the updates) policy
act_stats = compute_action_statistics(concat_ros,
self._expl_strat)
log_probs_new = act_stats.log_probs
act_distr_new = act_stats.act_distr
loss_after = self.loss_fcn(log_probs_new, log_probs_old, adv,
v_pred, v_pred_old, v_targ)
kl_avg = to.mean(kl_divergence(
act_distr_old,
act_distr_new)) # mean seeking a.k.a. inclusive KL
# Compute explained variance (after the updates)
explvar = explained_var(v_pred, v_targ)
self.logger.add_value('explained var',
explvar.detach().numpy())
self.logger.add_value('V-fcn loss improvement',
value_fcn_loss_impr.detach().numpy())
self.logger.add_value('loss after',
loss_after.detach().numpy())
self.logger.add_value('KL(old_new)', kl_avg.item())
# Logging
self.logger.add_value(
'avg expl strat std',
to.mean(self._expl_strat.noise.std.data).detach().numpy())
self.logger.add_value('expl strat entropy',
self._expl_strat.noise.get_entropy().item())
self.logger.add_value('avg policy grad norm',
np.mean(policy_grad_norm))
self.logger.add_value('avg V-fcn grad norm',
np.mean(value_fcn_grad_norm))
if self._lr_scheduler is not None:
self.logger.add_value('learning rate', self._lr_scheduler.get_lr())
def update(self, rollouts: Sequence[StepSequence]):
# Turn the batch of rollouts into a list of steps
concat_ros = StepSequence.concat(rollouts)
concat_ros.torch(data_type=to.get_default_dtype())
# Compute the value targets (empirical discounted returns) for all samples before fitting the V-fcn parameters
adv = self._critic.gae(concat_ros) # done with to.no_grad()
v_targ = discounted_values(rollouts, self._critic.gamma).view(-1, 1).to(self.policy.device) # empirical discounted returns
with to.no_grad():
# Compute value predictions and the GAE using the old (before the updates) value function approximator
v_pred = self._critic.values(concat_ros)
# Compute the action probabilities using the old (before update) policy
act_stats = compute_action_statistics(concat_ros, self._expl_strat)
log_probs_old = act_stats.log_probs
act_distr_old = act_stats.act_distr
loss_before = self.loss_fcn(log_probs_old, adv, v_pred, v_targ)
self.logger.add_value('loss before', loss_before, 4)
concat_ros.add_data('adv', adv)
concat_ros.add_data('v_targ', v_targ)
# For logging the gradients' norms
policy_grad_norm = []
for batch in tqdm(concat_ros.split_shuffled_batches(
self.batch_size,
complete_rollouts=self._policy.is_recurrent or isinstance(self._critic.vfcn, RecurrentPolicy)),
total=num_iter_from_rollouts(None, concat_ros, self.batch_size),
desc='Updating', unit='batches', file=sys.stdout, leave=False):
# Reset the gradients
self.optim.zero_grad()
# Compute log of the action probabilities for the mini-batch
log_probs = compute_action_statistics(batch, self._expl_strat).log_probs
# Compute value predictions for the mini-batch
v_pred = self._critic.values(batch)
# Compute combined loss and backpropagate
loss = self.loss_fcn(log_probs, batch.adv, v_pred, batch.v_targ)
loss.backward()
# Clip the gradients if desired
policy_grad_norm.append(self.clip_grad(self.expl_strat.policy, self.max_grad_norm))
# Call optimizer
self.optim.step()
# Update the learning rate if a scheduler has been specified
if self._lr_scheduler is not None:
self._lr_scheduler.step()
if to.isnan(self.expl_strat.noise.std).any():
raise RuntimeError(f'At least one exploration parameter became NaN! The exploration parameters are'
f'\n{self.expl_strat.std.item()}')
# Logging
with to.no_grad():
# Compute value predictions and the GAE using the new (after the updates) value function approximator
v_pred = self._critic.values(concat_ros).to(self.policy.device)
adv = self._critic.gae(concat_ros) # done with to.no_grad()
# Compute the action probabilities using the new (after the updates) policy
act_stats = compute_action_statistics(concat_ros, self._expl_strat)
log_probs_new = act_stats.log_probs
act_distr_new = act_stats.act_distr
loss_after = self.loss_fcn(log_probs_new, adv, v_pred, v_targ)
kl_avg = to.mean(
kl_divergence(act_distr_old, act_distr_new)) # mean seeking a.k.a. inclusive KL
explvar = explained_var(v_pred, v_targ) # values close to 1 are desired
self.logger.add_value('loss after', loss_after, 4)
self.logger.add_value('KL(old_new)', kl_avg, 4)
self.logger.add_value('explained var', explvar, 4)
ent = self.expl_strat.noise.get_entropy()
self.logger.add_value('avg expl strat std', to.mean(self.expl_strat.noise.std), 4)
self.logger.add_value('expl strat entropy', to.mean(ent), 4)
self.logger.add_value('avg grad norm policy', np.mean(policy_grad_norm), 4)
if self._lr_scheduler is not None:
self.logger.add_value('avg lr', np.mean(self._lr_scheduler.get_last_lr()), 6)