您最多选择25个主题
主题必须以中文或者字母或数字开头,可以包含连字符 (-),并且长度不得超过35个字符
279 行
11 KiB
279 行
11 KiB
# # Unity ML-Agents Toolkit
|
|
# ## ML-Agent Learning (PPO)
|
|
# Contains an implementation of PPO as described in: https://arxiv.org/abs/1707.06347
|
|
|
|
from collections import defaultdict
|
|
from typing import cast
|
|
|
|
import numpy as np
|
|
|
|
from mlagents_envs.logging_util import get_logger
|
|
from mlagents_envs.base_env import BehaviorSpec
|
|
from mlagents.trainers.trainer.rl_trainer import RLTrainer
|
|
from mlagents.trainers.policy import Policy
|
|
from mlagents.trainers.policy.tf_policy import TFPolicy
|
|
from mlagents.trainers.ppo.optimizer import PPOOptimizer
|
|
from mlagents.trainers.trajectory import Trajectory
|
|
from mlagents.trainers.behavior_id_utils import BehaviorIdentifiers
|
|
from mlagents.trainers.settings import TrainerSettings, PPOSettings
|
|
from mlagents.trainers.stats import StatsPropertyType
|
|
|
|
logger = get_logger(__name__)
|
|
|
|
|
|
class PPOTrainer(RLTrainer):
|
|
"""The PPOTrainer is an implementation of the PPO algorithm."""
|
|
|
|
def __init__(
|
|
self,
|
|
brain_name: str,
|
|
reward_buff_cap: int,
|
|
trainer_settings: TrainerSettings,
|
|
training: bool,
|
|
load: bool,
|
|
seed: int,
|
|
artifact_path: str,
|
|
):
|
|
"""
|
|
Responsible for collecting experiences and training PPO model.
|
|
:param brain_name: The name of the brain associated with trainer config
|
|
:param reward_buff_cap: Max reward history to track in the reward buffer
|
|
:param trainer_settings: The parameters for the trainer.
|
|
:param training: Whether the trainer is set for training.
|
|
:param load: Whether the model should be loaded.
|
|
:param seed: The seed the model will be initialized with
|
|
:param artifact_path: The directory within which to store artifacts from this trainer.
|
|
"""
|
|
super().__init__(
|
|
brain_name, trainer_settings, training, artifact_path, reward_buff_cap
|
|
)
|
|
self.hyperparameters: PPOSettings = cast(
|
|
PPOSettings, self.trainer_settings.hyperparameters
|
|
)
|
|
self.load = load
|
|
self.seed = seed
|
|
self.policy: Policy = None # type: ignore
|
|
|
|
def _process_trajectory(self, trajectory: Trajectory) -> None:
|
|
"""
|
|
Takes a trajectory and processes it, putting it into the update buffer.
|
|
Processing involves calculating value and advantage targets for model updating step.
|
|
:param trajectory: The Trajectory tuple containing the steps to be processed.
|
|
"""
|
|
super()._process_trajectory(trajectory)
|
|
agent_id = trajectory.agent_id # All the agents should have the same ID
|
|
|
|
agent_buffer_trajectory = trajectory.to_agentbuffer()
|
|
# Update the normalization
|
|
if self.is_training:
|
|
self.policy.update_normalization(agent_buffer_trajectory["vector_obs"])
|
|
|
|
# Get all value estimates
|
|
value_estimates, value_next = self.optimizer.get_trajectory_value_estimates(
|
|
agent_buffer_trajectory,
|
|
trajectory.next_obs,
|
|
trajectory.done_reached and not trajectory.interrupted,
|
|
)
|
|
|
|
saliencies = self.optimizer.get_saliency(agent_buffer_trajectory)
|
|
self._stats_reporter.add_property(StatsPropertyType.SALIENCY, saliencies)
|
|
|
|
for name, v in value_estimates.items():
|
|
agent_buffer_trajectory[f"{name}_value_estimates"].extend(v)
|
|
self._stats_reporter.add_stat(
|
|
self.optimizer.reward_signals[name].value_name, np.mean(v)
|
|
)
|
|
|
|
# Evaluate all reward functions
|
|
self.collected_rewards["environment"][agent_id] += np.sum(
|
|
agent_buffer_trajectory["environment_rewards"]
|
|
)
|
|
for name, reward_signal in self.optimizer.reward_signals.items():
|
|
evaluate_result = reward_signal.evaluate_batch(
|
|
agent_buffer_trajectory
|
|
).scaled_reward
|
|
agent_buffer_trajectory[f"{name}_rewards"].extend(evaluate_result)
|
|
# Report the reward signals
|
|
self.collected_rewards[name][agent_id] += np.sum(evaluate_result)
|
|
|
|
# Compute GAE and returns
|
|
tmp_advantages = []
|
|
tmp_returns = []
|
|
for name in self.optimizer.reward_signals:
|
|
bootstrap_value = value_next[name]
|
|
|
|
local_rewards = agent_buffer_trajectory[f"{name}_rewards"].get_batch()
|
|
local_value_estimates = agent_buffer_trajectory[
|
|
f"{name}_value_estimates"
|
|
].get_batch()
|
|
local_advantage = get_gae(
|
|
rewards=local_rewards,
|
|
value_estimates=local_value_estimates,
|
|
value_next=bootstrap_value,
|
|
gamma=self.optimizer.reward_signals[name].gamma,
|
|
lambd=self.hyperparameters.lambd,
|
|
)
|
|
local_return = local_advantage + local_value_estimates
|
|
# This is later use as target for the different value estimates
|
|
agent_buffer_trajectory[f"{name}_returns"].set(local_return)
|
|
agent_buffer_trajectory[f"{name}_advantage"].set(local_advantage)
|
|
tmp_advantages.append(local_advantage)
|
|
tmp_returns.append(local_return)
|
|
|
|
# Get global advantages
|
|
global_advantages = list(
|
|
np.mean(np.array(tmp_advantages, dtype=np.float32), axis=0)
|
|
)
|
|
global_returns = list(np.mean(np.array(tmp_returns, dtype=np.float32), axis=0))
|
|
agent_buffer_trajectory["advantages"].set(global_advantages)
|
|
agent_buffer_trajectory["discounted_returns"].set(global_returns)
|
|
# Append to update buffer
|
|
agent_buffer_trajectory.resequence_and_append(
|
|
self.update_buffer, training_length=self.policy.sequence_length
|
|
)
|
|
|
|
# If this was a terminal trajectory, append stats and reset reward collection
|
|
if trajectory.done_reached:
|
|
self._update_end_episode_stats(agent_id, self.optimizer)
|
|
|
|
def _is_ready_update(self):
|
|
"""
|
|
Returns whether or not the trainer has enough elements to run update model
|
|
:return: A boolean corresponding to whether or not update_model() can be run
|
|
"""
|
|
size_of_buffer = self.update_buffer.num_experiences
|
|
return size_of_buffer > self.hyperparameters.buffer_size
|
|
|
|
def _update_policy(self):
|
|
"""
|
|
Uses demonstration_buffer to update the policy.
|
|
The reward signal generators must be updated in this method at their own pace.
|
|
"""
|
|
buffer_length = self.update_buffer.num_experiences
|
|
self.cumulative_returns_since_policy_update.clear()
|
|
|
|
# Make sure batch_size is a multiple of sequence length. During training, we
|
|
# will need to reshape the data into a batch_size x sequence_length tensor.
|
|
batch_size = (
|
|
self.hyperparameters.batch_size
|
|
- self.hyperparameters.batch_size % self.policy.sequence_length
|
|
)
|
|
# Make sure there is at least one sequence
|
|
batch_size = max(batch_size, self.policy.sequence_length)
|
|
|
|
n_sequences = max(
|
|
int(self.hyperparameters.batch_size / self.policy.sequence_length), 1
|
|
)
|
|
|
|
advantages = self.update_buffer["advantages"].get_batch()
|
|
self.update_buffer["advantages"].set(
|
|
(advantages - advantages.mean()) / (advantages.std() + 1e-10)
|
|
)
|
|
num_epoch = self.hyperparameters.num_epoch
|
|
batch_update_stats = defaultdict(list)
|
|
|
|
for _ in range(num_epoch):
|
|
self.update_buffer.shuffle(sequence_length=self.policy.sequence_length)
|
|
buffer = self.update_buffer
|
|
max_num_batch = buffer_length // batch_size
|
|
for i in range(0, max_num_batch * batch_size, batch_size):
|
|
update_stats = self.optimizer.update(
|
|
buffer.make_mini_batch(i, i + batch_size), n_sequences
|
|
)
|
|
for stat_name, value in update_stats.items():
|
|
batch_update_stats[stat_name].append(value)
|
|
|
|
for stat, stat_list in batch_update_stats.items():
|
|
self._stats_reporter.add_stat(stat, np.mean(stat_list))
|
|
|
|
if self.optimizer.bc_module:
|
|
update_stats = self.optimizer.bc_module.update()
|
|
for stat, val in update_stats.items():
|
|
self._stats_reporter.add_stat(stat, val)
|
|
self._clear_update_buffer()
|
|
return True
|
|
|
|
def create_policy(
|
|
self, parsed_behavior_id: BehaviorIdentifiers, behavior_spec: BehaviorSpec
|
|
) -> TFPolicy:
|
|
"""
|
|
Creates a PPO policy to trainers list of policies.
|
|
:param behavior_spec: specifications for policy construction
|
|
:return policy
|
|
"""
|
|
policy = TFPolicy(
|
|
self.seed,
|
|
behavior_spec,
|
|
self.trainer_settings,
|
|
model_path=self.artifact_path,
|
|
load=self.load,
|
|
condition_sigma_on_obs=False, # Faster training for PPO
|
|
create_tf_graph=False, # We will create the TF graph in the Optimizer
|
|
)
|
|
|
|
return policy
|
|
|
|
def add_policy(
|
|
self, parsed_behavior_id: BehaviorIdentifiers, policy: Policy
|
|
) -> None:
|
|
"""
|
|
Adds policy to trainer.
|
|
:param parsed_behavior_id: Behavior identifiers that the policy should belong to.
|
|
:param policy: Policy to associate with name_behavior_id.
|
|
"""
|
|
if self.policy:
|
|
logger.warning(
|
|
"Your environment contains multiple teams, but {} doesn't support adversarial games. Enable self-play to \
|
|
train adversarial games.".format(
|
|
self.__class__.__name__
|
|
)
|
|
)
|
|
self.policy = policy
|
|
self.policies[parsed_behavior_id.behavior_id] = policy
|
|
self.optimizer = PPOOptimizer(
|
|
cast(TFPolicy, self.policy), self.trainer_settings
|
|
)
|
|
for _reward_signal in self.optimizer.reward_signals.keys():
|
|
self.collected_rewards[_reward_signal] = defaultdict(lambda: 0)
|
|
# Needed to resume loads properly
|
|
self.step = policy.get_current_step()
|
|
|
|
def get_policy(self, name_behavior_id: str) -> Policy:
|
|
"""
|
|
Gets policy from trainer associated with name_behavior_id
|
|
:param name_behavior_id: full identifier of policy
|
|
"""
|
|
|
|
return self.policy
|
|
|
|
|
|
def discount_rewards(r, gamma=0.99, value_next=0.0):
|
|
"""
|
|
Computes discounted sum of future rewards for use in updating value estimate.
|
|
:param r: List of rewards.
|
|
:param gamma: Discount factor.
|
|
:param value_next: T+1 value estimate for returns calculation.
|
|
:return: discounted sum of future rewards as list.
|
|
"""
|
|
discounted_r = np.zeros_like(r)
|
|
running_add = value_next
|
|
for t in reversed(range(0, r.size)):
|
|
running_add = running_add * gamma + r[t]
|
|
discounted_r[t] = running_add
|
|
return discounted_r
|
|
|
|
|
|
def get_gae(rewards, value_estimates, value_next=0.0, gamma=0.99, lambd=0.95):
|
|
"""
|
|
Computes generalized advantage estimate for use in updating policy.
|
|
:param rewards: list of rewards for time-steps t to T.
|
|
:param value_next: Value estimate for time-step T+1.
|
|
:param value_estimates: list of value estimates for time-steps t to T.
|
|
:param gamma: Discount factor.
|
|
:param lambd: GAE weighing factor.
|
|
:return: list of advantage estimates for time-steps t to T.
|
|
"""
|
|
value_estimates = np.append(value_estimates, value_next)
|
|
delta_t = rewards + gamma * value_estimates[1:] - value_estimates[:-1]
|
|
advantage = discount_rewards(r=delta_t, gamma=gamma * lambd)
|
|
return advantage
|