def testBadMask(self):
input_tensor = tf.reshape(tf.range(12, dtype=tf.float32), shape=[3, 4])
mask = [[1, 0, 0, 1], [0, 0, 0, 0], [1, 0, 1, 1]]
expected = [3, -1, 3]
actual = self.evaluate(
policy_utilities.masked_argmax(input_tensor, tf.constant(mask)))
self.assertAllEqual(actual, expected)
def _distribution(self, time_step, policy_state):
if time_step.step_type.shape:
if tf.is_tensor(time_step.step_type
) and time_step.step_type.shape.rank > 0:
batch_size = time_step.step_type.get_shape().as_list()[0]
else:
batch_size = 1
else:
batch_size = 1
# Sample from the posterior distribution.
posterior_dist = tfd.Beta(self._alpha, self._beta)
predicted_reward_sampled = posterior_dist.sample([batch_size])
predicted_reward_means_1d = tf.stack([
self._alpha[k] / (self._alpha[k] + self._beta[k])
for k in range(self._expected_num_actions)
],
axis=-1)
predicted_reward_means = tf.stack(
[predicted_reward_means_1d for k in range(batch_size)], axis=0)
mask = None
if self._observation_and_action_constraint_splitter is not None:
_, mask = self._observation_and_action_constraint_splitter(
time_step.observation)
# Argmax.
if mask is not None:
actions = policy_utilities.masked_argmax(
predicted_reward_sampled,
mask,
output_type=self.action_spec.dtype)
else:
actions = tf.argmax(predicted_reward_sampled,
axis=-1,
output_type=self.action_spec.dtype)
policy_info = policy_utilities.populate_policy_info(
arm_observations=(),
chosen_actions=actions,
rewards_for_argmax=tf.cast(predicted_reward_sampled, tf.float32),
est_rewards=tf.cast(predicted_reward_means, tf.float32),
emit_policy_info=self._emit_policy_info,
accepts_per_arm_features=False)
if policy_utilities.InfoFields.LOG_PROBABILITY in self._emit_policy_info:
policy_info._replace(
log_probability=tf.zeros([batch_size], tf.float32))
return policy_step.PolicyStep(
tfp.distributions.Deterministic(loc=actions), policy_state,
policy_info)
def _get_actions_from_linucb(
self, encoded_observation: types.Float, mask: Optional[types.Tensor]
) -> Tuple[types.Int, types.Float, types.Float]:
encoded_observation = tf.cast(encoded_observation, dtype=self._dtype)
p_values = []
est_rewards = []
for k in range(self._num_actions):
encoded_observation_for_arm = self._get_encoded_observation_for_arm(
encoded_observation, k)
model_index = policy_utilities.get_model_index(
k, self._accepts_per_arm_features)
a_inv_x = linalg.conjugate_gradient_solve(
self._cov_matrix[model_index] +
tf.eye(self._encoding_dim, dtype=self._dtype),
tf.linalg.matrix_transpose(encoded_observation_for_arm))
mean_reward_est = tf.einsum('j,jk->k',
self._data_vector[model_index],
a_inv_x)
est_rewards.append(mean_reward_est)
ci = tf.reshape(
tf.linalg.tensor_diag_part(
tf.matmul(encoded_observation_for_arm, a_inv_x)), [-1, 1])
p_values.append(
tf.reshape(mean_reward_est, [-1, 1]) +
self._alpha * tf.sqrt(ci))
stacked_p_values = tf.squeeze(tf.stack(p_values, axis=-1), axis=[1])
if mask is None:
chosen_actions = tf.argmax(stacked_p_values,
axis=-1,
output_type=tf.int32)
else:
chosen_actions = policy_utilities.masked_argmax(
stacked_p_values, mask, output_type=tf.int32)
est_mean_reward = tf.cast(tf.stack(est_rewards, axis=-1), tf.float32)
return chosen_actions, est_mean_reward, tf.cast(
stacked_p_values, tf.float32)
def _get_actions_from_reward_layer(
self, encoded_observation: types.Float, mask: Optional[types.Tensor]
) -> Tuple[types.Int, types.Float, types.Float]:
# Get the predicted expected reward.
est_mean_reward = tf.reshape(self._reward_layer(encoded_observation),
shape=[-1, self._num_actions])
if mask is None:
greedy_actions = tf.argmax(est_mean_reward,
axis=-1,
output_type=tf.int32)
else:
greedy_actions = policy_utilities.masked_argmax(
est_mean_reward, mask, output_type=tf.int32)
# Add epsilon greedy on top, if needed.
if self._epsilon_greedy:
batch_size = (tf.compat.dimension_value(
encoded_observation.shape[0])
or tf.shape(encoded_observation)[0])
if mask is None:
random_actions = tf.random.uniform([batch_size],
maxval=self._num_actions,
dtype=tf.int32)
else:
zero_logits = tf.cast(tf.zeros_like(mask), tf.float32)
masked_categorical = masked.MaskedCategorical(zero_logits,
mask,
dtype=tf.int32)
random_actions = masked_categorical.sample()
rng = tf.random.uniform([batch_size], maxval=1.0)
cond = tf.greater(rng, self._epsilon_greedy)
chosen_actions = tf.compat.v1.where(cond, greedy_actions,
random_actions)
else:
chosen_actions = greedy_actions
return chosen_actions, est_mean_reward, est_mean_reward
def testMaskedArgmax(self, input_tensor, mask, expected):
actual = policy_utilities.masked_argmax(
tf.constant(input_tensor, dtype=tf.float32), tf.constant(mask))
self.assertAllEqual(actual, expected)
def _distribution(self, time_step, policy_state):
observation = time_step.observation
if self.observation_and_action_constraint_splitter is not None:
observation, _ = self.observation_and_action_constraint_splitter(
observation)
observation = tf.nest.map_structure(
lambda o: tf.cast(o, dtype=self._dtype), observation)
global_observation, arm_observations = self._split_observation(
observation)
if self._add_bias:
# The bias is added via a constant 1 feature.
global_observation = tf.concat([
global_observation,
tf.ones([tf.shape(global_observation)[0], 1],
dtype=self._dtype)
],
axis=1)
# Check the shape of the observation matrix. The observations can be
# batched.
if not global_observation.shape.is_compatible_with(
[None, self._global_context_dim]):
raise ValueError(
'Global observation shape is expected to be {}. Got {}.'.
format([None, self._global_context_dim],
global_observation.shape.as_list()))
global_observation = tf.reshape(global_observation,
[-1, self._global_context_dim])
est_rewards = []
confidence_intervals = []
for k in range(self._num_actions):
current_observation = self._get_current_observation(
global_observation, arm_observations, k)
model_index = policy_utilities.get_model_index(
k, self._accepts_per_arm_features)
if self._use_eigendecomp:
q_t_b = tf.matmul(
self._eig_matrix[model_index],
tf.linalg.matrix_transpose(current_observation),
transpose_a=True)
lambda_inv = tf.divide(
tf.ones_like(self._eig_vals[model_index]),
self._eig_vals[model_index] + self._tikhonov_weight)
a_inv_x = tf.matmul(self._eig_matrix[model_index],
tf.einsum('j,jk->jk', lambda_inv, q_t_b))
else:
a_inv_x = linalg.conjugate_gradient(
self._cov_matrix[model_index] + self._tikhonov_weight *
tf.eye(self._overall_context_dim, dtype=self._dtype),
tf.linalg.matrix_transpose(current_observation))
est_mean_reward = tf.einsum('j,jk->k',
self._data_vector[model_index],
a_inv_x)
est_rewards.append(est_mean_reward)
ci = tf.reshape(
tf.linalg.tensor_diag_part(
tf.matmul(current_observation, a_inv_x)), [-1, 1])
confidence_intervals.append(ci)
if self._exploration_strategy == ExplorationStrategy.optimistic:
optimistic_estimates = [
tf.reshape(mean_reward, [-1, 1]) +
self._alpha * tf.sqrt(confidence)
for mean_reward, confidence in zip(est_rewards,
confidence_intervals)
]
# Keeping the batch dimension during the squeeze, even if batch_size == 1.
rewards_for_argmax = tf.squeeze(tf.stack(optimistic_estimates,
axis=-1),
axis=[1])
elif self._exploration_strategy == ExplorationStrategy.sampling:
mu_sampler = tfd.Normal(
loc=tf.stack(est_rewards, axis=-1),
scale=self._alpha * tf.sqrt(
tf.squeeze(tf.stack(confidence_intervals, axis=-1),
axis=1)))
rewards_for_argmax = mu_sampler.sample()
else:
raise ValueError('Exploraton strategy %s not implemented.' %
self._exploration_strategy)
mask = constraints.construct_mask_from_multiple_sources(
time_step.observation,
self._observation_and_action_constraint_splitter, (),
self._num_actions)
if mask is not None:
chosen_actions = policy_utilities.masked_argmax(
rewards_for_argmax,
mask,
output_type=tf.nest.flatten(self._action_spec)[0].dtype)
else:
chosen_actions = tf.argmax(rewards_for_argmax,
axis=-1,
output_type=tf.nest.flatten(
self._action_spec)[0].dtype)
action_distributions = tfp.distributions.Deterministic(
loc=chosen_actions)
policy_info = policy_utilities.populate_policy_info(
arm_observations, chosen_actions, rewards_for_argmax,
tf.stack(est_rewards, axis=-1), self._emit_policy_info,
self._accepts_per_arm_features)
return policy_step.PolicyStep(action_distributions, policy_state,
policy_info)
def _distribution(self, time_step, policy_state):
observation = time_step.observation
if self.observation_and_action_constraint_splitter is not None:
observation, _ = self.observation_and_action_constraint_splitter(
observation)
predictions, policy_state = self._reward_network(
observation, time_step.step_type, policy_state)
batch_size = tf.shape(predictions)[0]
if isinstance(self._reward_network,
heteroscedastic_q_network.HeteroscedasticQNetwork):
predicted_reward_values = predictions.q_value_logits
else:
predicted_reward_values = predictions
predicted_reward_values.shape.with_rank_at_least(2)
predicted_reward_values.shape.with_rank_at_most(3)
if predicted_reward_values.shape[
-1] is not None and predicted_reward_values.shape[
-1] != self._expected_num_actions:
raise ValueError(
'The number of actions ({}) does not match the reward_network output'
' size ({}).'.format(self._expected_num_actions,
predicted_reward_values.shape[1]))
mask = constr.construct_mask_from_multiple_sources(
time_step.observation, self._observation_and_action_constraint_splitter,
self._constraints, self._expected_num_actions)
# Argmax.
if mask is not None:
actions = policy_utilities.masked_argmax(
predicted_reward_values, mask, output_type=self.action_spec.dtype)
else:
actions = tf.argmax(
predicted_reward_values, axis=-1, output_type=self.action_spec.dtype)
actions += self._action_offset
bandit_policy_values = tf.fill([batch_size, 1],
policy_utilities.BanditPolicyType.GREEDY)
if self._accepts_per_arm_features:
# Saving the features for the chosen action to the policy_info.
def gather_observation(obs):
return tf.gather(params=obs, indices=actions, batch_dims=1)
chosen_arm_features = tf.nest.map_structure(
gather_observation,
observation[bandit_spec_utils.PER_ARM_FEATURE_KEY])
policy_info = policy_utilities.PerArmPolicyInfo(
log_probability=tf.zeros([batch_size], tf.float32) if
policy_utilities.InfoFields.LOG_PROBABILITY in self._emit_policy_info
else (),
predicted_rewards_mean=(
predicted_reward_values if policy_utilities.InfoFields
.PREDICTED_REWARDS_MEAN in self._emit_policy_info else ()),
bandit_policy_type=(bandit_policy_values
if policy_utilities.InfoFields.BANDIT_POLICY_TYPE
in self._emit_policy_info else ()),
chosen_arm_features=chosen_arm_features)
else:
policy_info = policy_utilities.PolicyInfo(
log_probability=tf.zeros([batch_size], tf.float32) if
policy_utilities.InfoFields.LOG_PROBABILITY in self._emit_policy_info
else (),
predicted_rewards_mean=(
predicted_reward_values if policy_utilities.InfoFields
.PREDICTED_REWARDS_MEAN in self._emit_policy_info else ()),
bandit_policy_type=(bandit_policy_values
if policy_utilities.InfoFields.BANDIT_POLICY_TYPE
in self._emit_policy_info else ()))
return policy_step.PolicyStep(
tfp.distributions.Deterministic(loc=actions), policy_state, policy_info)
def _distribution(
self, time_step: ts.TimeStep,
policy_state: Sequence[types.TensorSpec]
) -> policy_step.PolicyStep:
observation = time_step.observation
if self.observation_and_action_constraint_splitter is not None:
observation, _ = self.observation_and_action_constraint_splitter(
observation)
predicted_objective_values_tensor, policy_state = self._predict(
observation, time_step.step_type, policy_state)
scalarized_reward = scalarize_objectives(
predicted_objective_values_tensor, self._scalarizer)
# Preserve static batch size values when they are available.
batch_size = (tf.compat.dimension_value(scalarized_reward.shape[0])
or tf.shape(scalarized_reward)[0])
mask = constraints.construct_mask_from_multiple_sources(
time_step.observation,
self._observation_and_action_constraint_splitter, (),
self._expected_num_actions)
# Argmax.
if mask is not None:
actions = policy_utilities.masked_argmax(
scalarized_reward, mask, output_type=self.action_spec.dtype)
else:
actions = tf.argmax(scalarized_reward,
axis=-1,
output_type=self.action_spec.dtype)
actions += self._action_offset
bandit_policy_values = tf.fill(
[batch_size, 1], policy_utilities.BanditPolicyType.GREEDY)
if self._accepts_per_arm_features:
# Saving the features for the chosen action to the policy_info.
def gather_observation(obs):
return tf.gather(params=obs, indices=actions, batch_dims=1)
chosen_arm_features = tf.nest.map_structure(
gather_observation,
observation[bandit_spec_utils.PER_ARM_FEATURE_KEY])
policy_info = policy_utilities.PerArmPolicyInfo(
log_probability=tf.zeros([batch_size], tf.float32)
if policy_utilities.InfoFields.LOG_PROBABILITY
in self._emit_policy_info else (),
predicted_rewards_mean=(
predicted_objective_values_tensor
if policy_utilities.InfoFields.PREDICTED_REWARDS_MEAN
in self._emit_policy_info else ()),
multiobjective_scalarized_predicted_rewards_mean=(
scalarized_reward if policy_utilities.InfoFields.
MULTIOBJECTIVE_SCALARIZED_PREDICTED_REWARDS_MEAN
in self._emit_policy_info else ()),
bandit_policy_type=(
bandit_policy_values
if policy_utilities.InfoFields.BANDIT_POLICY_TYPE
in self._emit_policy_info else ()),
chosen_arm_features=chosen_arm_features)
else:
policy_info = policy_utilities.PolicyInfo(
log_probability=tf.zeros([batch_size], tf.float32)
if policy_utilities.InfoFields.LOG_PROBABILITY
in self._emit_policy_info else (),
predicted_rewards_mean=(
predicted_objective_values_tensor
if policy_utilities.InfoFields.PREDICTED_REWARDS_MEAN
in self._emit_policy_info else ()),
multiobjective_scalarized_predicted_rewards_mean=(
scalarized_reward if policy_utilities.InfoFields.
MULTIOBJECTIVE_SCALARIZED_PREDICTED_REWARDS_MEAN
in self._emit_policy_info else ()),
bandit_policy_type=(
bandit_policy_values
if policy_utilities.InfoFields.BANDIT_POLICY_TYPE
in self._emit_policy_info else ()))
return policy_step.PolicyStep(
tfp.distributions.Deterministic(loc=actions), policy_state,
policy_info)