def train_bc(self, expert_dataset_iter):
"""Performs a single training step of behavior clonning.
The method optimizes MLE on the expert dataset.
Args:
expert_dataset_iter: An tensorflow graph iteratable object.
"""
with tf.GradientTape(watch_accessed_variables=False) as tape:
tape.watch(self.actor.variables)
states, actions, _ = next(expert_dataset_iter)
log_probs = self.actor.get_log_prob(states, actions)
actor_loss = tf.reduce_mean(
-log_probs) + keras_utils.orthogonal_regularization(
self.actor.trunk)
actor_grads = tape.gradient(actor_loss, self.actor.variables)
self.actor_optimizer.apply_gradients(
zip(actor_grads, self.actor.variables))
self.avg_actor_loss(actor_loss)
if tf.equal(self.actor_optimizer.iterations % self.log_interval, 0):
tf.summary.scalar('train bc/actor_loss',
self.avg_actor_loss.result(),
step=self.actor_optimizer.iterations)
keras_utils.my_reset_states(self.avg_actor_loss)
def fit_actor(self, states, target_entropy):
"""Updates actor parameters.
Args:
states: A batch of states.
target_entropy: Target entropy value for alpha.
Returns:
Actor and alpha losses.
"""
is_non_absorbing_mask = tf.cast(tf.equal(states[:, -1:], 0.0),
tf.float32)
with tf.GradientTape(watch_accessed_variables=False) as tape:
tape.watch(self.actor.variables)
_, actions, log_probs = self.actor(states)
q1, q2 = self.critic(states, actions)
q = tf.minimum(q1, q2)
actor_loss = tf.reduce_sum(
is_non_absorbing_mask * (self.alpha * log_probs - q)) / (
tf.reduce_sum(is_non_absorbing_mask) + EPS)
actor_loss += keras_utils.orthogonal_regularization(
self.actor.trunk)
actor_grads = tape.gradient(actor_loss, self.actor.variables)
self.actor_optimizer.apply_gradients(
zip(actor_grads, self.actor.variables))
with tf.GradientTape(watch_accessed_variables=False) as tape:
tape.watch([self.log_alpha])
alpha_loss = tf.reduce_sum(
is_non_absorbing_mask * self.alpha *
(-log_probs - target_entropy)) / (
tf.reduce_sum(is_non_absorbing_mask) + EPS)
if self.learn_alpha:
alpha_grads = tape.gradient(alpha_loss, [self.log_alpha])
self.alpha_optimizer.apply_gradients(
zip(alpha_grads, [self.log_alpha]))
return actor_loss, alpha_loss, -log_probs
def update(self,
expert_dataset_iter,
policy_dataset_iter,
discount,
replay_regularization=0.05,
nu_reg=10.0):
"""A function that updates nu network.
When replay regularization is non-zero, it learns
(d_pi * (1 - replay_regularization) + d_rb * replay_regulazation) /
(d_expert * (1 - replay_regularization) + d_rb * replay_regulazation)
instead.
Args:
expert_dataset_iter: An tensorflow graph iteratable over expert data.
policy_dataset_iter: An tensorflow graph iteratable over training policy
data, used for regularization.
discount: An MDP discount.
replay_regularization: A fraction of samples to add from a replay buffer.
nu_reg: A grad penalty regularization coefficient.
"""
(expert_states, expert_actions,
expert_next_states) = expert_dataset_iter.get_next()
expert_initial_states = expert_states
rb_states, rb_actions, rb_next_states, _, _ = policy_dataset_iter.get_next(
)[0]
with tf.GradientTape(watch_accessed_variables=False,
persistent=True) as tape:
tape.watch(self.actor.variables)
tape.watch(self.nu_net.variables)
_, policy_next_actions, _ = self.actor(expert_next_states)
_, rb_next_actions, rb_log_prob = self.actor(rb_next_states)
_, policy_initial_actions, _ = self.actor(expert_initial_states)
# Inputs for the linear part of DualDICE loss.
expert_init_inputs = tf.concat(
[expert_initial_states, policy_initial_actions], 1)
expert_inputs = tf.concat([expert_states, expert_actions], 1)
expert_next_inputs = tf.concat(
[expert_next_states, policy_next_actions], 1)
rb_inputs = tf.concat([rb_states, rb_actions], 1)
rb_next_inputs = tf.concat([rb_next_states, rb_next_actions], 1)
expert_nu_0 = self.nu_net(expert_init_inputs)
expert_nu = self.nu_net(expert_inputs)
expert_nu_next = self.nu_net(expert_next_inputs)
rb_nu = self.nu_net(rb_inputs)
rb_nu_next = self.nu_net(rb_next_inputs)
expert_diff = expert_nu - discount * expert_nu_next
rb_diff = rb_nu - discount * rb_nu_next
linear_loss_expert = tf.reduce_mean(expert_nu_0 * (1 - discount))
linear_loss_rb = tf.reduce_mean(rb_diff)
rb_expert_diff = tf.concat([expert_diff, rb_diff], 0)
rb_expert_weights = tf.concat([
tf.ones(expert_diff.shape) * (1 - replay_regularization),
tf.ones(rb_diff.shape) * replay_regularization
], 0)
rb_expert_weights /= tf.reduce_sum(rb_expert_weights)
non_linear_loss = tf.reduce_sum(
tf.stop_gradient(
weighted_softmax(rb_expert_diff, rb_expert_weights,
axis=0)) * rb_expert_diff)
linear_loss = (linear_loss_expert * (1 - replay_regularization) +
linear_loss_rb * replay_regularization)
loss = (non_linear_loss - linear_loss)
alpha = tf.random.uniform(shape=(expert_inputs.shape[0], 1))
nu_inter = alpha * expert_inputs + (1 - alpha) * rb_inputs
nu_next_inter = alpha * expert_next_inputs + (
1 - alpha) * rb_next_inputs
nu_inter = tf.concat([nu_inter, nu_next_inter], 0)
with tf.GradientTape(watch_accessed_variables=False) as tape2:
tape2.watch(nu_inter)
nu_output = self.nu_net(nu_inter)
nu_grad = tape2.gradient(nu_output, [nu_inter])[0] + EPS
nu_grad_penalty = tf.reduce_mean(
tf.square(tf.norm(nu_grad, axis=-1, keepdims=True) - 1))
nu_loss = loss + nu_grad_penalty * nu_reg
pi_loss = -loss + keras_utils.orthogonal_regularization(
self.actor.trunk)
nu_grads = tape.gradient(nu_loss, self.nu_net.variables)
pi_grads = tape.gradient(pi_loss, self.actor.variables)
self.nu_optimizer.apply_gradients(zip(nu_grads, self.nu_net.variables))
self.actor_optimizer.apply_gradients(
zip(pi_grads, self.actor.variables))
del tape
self.avg_nu_expert(expert_nu)
self.avg_nu_rb(rb_nu)
self.nu_reg_metric(nu_grad_penalty)
self.avg_loss(loss)
self.avg_actor_loss(pi_loss)
self.avg_actor_entropy(-rb_log_prob)
if tf.equal(self.nu_optimizer.iterations % self.log_interval, 0):
tf.summary.scalar('train dual dice/loss',
self.avg_loss.result(),
step=self.nu_optimizer.iterations)
keras_utils.my_reset_states(self.avg_loss)
tf.summary.scalar('train dual dice/nu expert',
self.avg_nu_expert.result(),
step=self.nu_optimizer.iterations)
keras_utils.my_reset_states(self.avg_nu_expert)
tf.summary.scalar('train dual dice/nu rb',
self.avg_nu_rb.result(),
step=self.nu_optimizer.iterations)
keras_utils.my_reset_states(self.avg_nu_rb)
tf.summary.scalar('train dual dice/nu reg',
self.nu_reg_metric.result(),
step=self.nu_optimizer.iterations)
keras_utils.my_reset_states(self.nu_reg_metric)
if tf.equal(self.actor_optimizer.iterations % self.log_interval, 0):
tf.summary.scalar('train sac/actor_loss',
self.avg_actor_loss.result(),
step=self.actor_optimizer.iterations)
keras_utils.my_reset_states(self.avg_actor_loss)
tf.summary.scalar('train sac/actor entropy',
self.avg_actor_entropy.result(),
step=self.actor_optimizer.iterations)
keras_utils.my_reset_states(self.avg_actor_entropy)