188 lines
8.8 KiB
Python
188 lines
8.8 KiB
Python
# SPDX-FileCopyrightText: Copyright (c) 2021 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
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# SPDX-License-Identifier: BSD-3-Clause
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice, this
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# list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# Copyright (c) 2021 ETH Zurich, Nikita Rudin
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import torch
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import torch.nn as nn
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import torch.optim as optim
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from rsl_rl.modules import ActorCritic
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from rsl_rl.storage import RolloutStorage
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class PPO:
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actor_critic: ActorCritic
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def __init__(self,
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actor_critic,
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num_learning_epochs=1,
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num_mini_batches=1,
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clip_param=0.2,
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gamma=0.998,
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lam=0.95,
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value_loss_coef=1.0,
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entropy_coef=0.0,
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learning_rate=1e-3,
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max_grad_norm=1.0,
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use_clipped_value_loss=True,
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schedule="fixed",
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desired_kl=0.01,
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device='cpu',
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):
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self.device = device
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self.desired_kl = desired_kl
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self.schedule = schedule
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self.learning_rate = learning_rate
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# PPO components
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self.actor_critic = actor_critic
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self.actor_critic.to(self.device)
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self.storage = None # initialized later
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self.optimizer = optim.Adam(self.actor_critic.parameters(), lr=learning_rate)
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self.transition = RolloutStorage.Transition()
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# PPO parameters
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self.clip_param = clip_param
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self.num_learning_epochs = num_learning_epochs
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self.num_mini_batches = num_mini_batches
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self.value_loss_coef = value_loss_coef
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self.entropy_coef = entropy_coef
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self.gamma = gamma
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self.lam = lam
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self.max_grad_norm = max_grad_norm
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self.use_clipped_value_loss = use_clipped_value_loss
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def init_storage(self, num_envs, num_transitions_per_env, actor_obs_shape, critic_obs_shape, action_shape):
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self.storage = RolloutStorage(num_envs, num_transitions_per_env, actor_obs_shape, critic_obs_shape, action_shape, self.device)
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def test_mode(self):
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self.actor_critic.test()
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def train_mode(self):
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self.actor_critic.train()
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def act(self, obs, critic_obs):
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if self.actor_critic.is_recurrent:
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self.transition.hidden_states = self.actor_critic.get_hidden_states()
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# Compute the actions and values
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self.transition.actions = self.actor_critic.act(obs).detach()
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self.transition.values = self.actor_critic.evaluate(critic_obs).detach()
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self.transition.actions_log_prob = self.actor_critic.get_actions_log_prob(self.transition.actions).detach()
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self.transition.action_mean = self.actor_critic.action_mean.detach()
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self.transition.action_sigma = self.actor_critic.action_std.detach()
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# need to record obs and critic_obs before env.step()
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self.transition.observations = obs
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self.transition.critic_observations = critic_obs
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return self.transition.actions
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def process_env_step(self, rewards, dones, infos):
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self.transition.rewards = rewards.clone()
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self.transition.dones = dones
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# Bootstrapping on time outs
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if 'time_outs' in infos:
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self.transition.rewards += self.gamma * torch.squeeze(self.transition.values * infos['time_outs'].unsqueeze(1).to(self.device), 1)
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# Record the transition
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self.storage.add_transitions(self.transition)
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self.transition.clear()
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self.actor_critic.reset(dones)
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def compute_returns(self, last_critic_obs):
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last_values= self.actor_critic.evaluate(last_critic_obs).detach()
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self.storage.compute_returns(last_values, self.gamma, self.lam)
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def update(self):
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mean_value_loss = 0
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mean_surrogate_loss = 0
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if self.actor_critic.is_recurrent:
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generator = self.storage.reccurent_mini_batch_generator(self.num_mini_batches, self.num_learning_epochs)
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else:
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generator = self.storage.mini_batch_generator(self.num_mini_batches, self.num_learning_epochs)
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for obs_batch, critic_obs_batch, actions_batch, target_values_batch, advantages_batch, returns_batch, old_actions_log_prob_batch, \
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old_mu_batch, old_sigma_batch, hid_states_batch, masks_batch in generator:
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self.actor_critic.act(obs_batch, masks=masks_batch, hidden_states=hid_states_batch[0])
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actions_log_prob_batch = self.actor_critic.get_actions_log_prob(actions_batch)
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value_batch = self.actor_critic.evaluate(critic_obs_batch, masks=masks_batch, hidden_states=hid_states_batch[1])
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mu_batch = self.actor_critic.action_mean
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sigma_batch = self.actor_critic.action_std
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entropy_batch = self.actor_critic.entropy
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# KL
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if self.desired_kl != None and self.schedule == 'adaptive':
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with torch.inference_mode():
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kl = torch.sum(
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torch.log(sigma_batch / old_sigma_batch + 1.e-5) + (torch.square(old_sigma_batch) + torch.square(old_mu_batch - mu_batch)) / (2.0 * torch.square(sigma_batch)) - 0.5, axis=-1)
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kl_mean = torch.mean(kl)
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if kl_mean > self.desired_kl * 2.0:
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self.learning_rate = max(1e-5, self.learning_rate / 1.5)
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elif kl_mean < self.desired_kl / 2.0 and kl_mean > 0.0:
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self.learning_rate = min(1e-2, self.learning_rate * 1.5)
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for param_group in self.optimizer.param_groups:
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param_group['lr'] = self.learning_rate
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# Surrogate loss
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ratio = torch.exp(actions_log_prob_batch - torch.squeeze(old_actions_log_prob_batch))
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surrogate = -torch.squeeze(advantages_batch) * ratio
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surrogate_clipped = -torch.squeeze(advantages_batch) * torch.clamp(ratio, 1.0 - self.clip_param,
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1.0 + self.clip_param)
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surrogate_loss = torch.max(surrogate, surrogate_clipped).mean()
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# Value function loss
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if self.use_clipped_value_loss:
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value_clipped = target_values_batch + (value_batch - target_values_batch).clamp(-self.clip_param,
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self.clip_param)
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value_losses = (value_batch - returns_batch).pow(2)
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value_losses_clipped = (value_clipped - returns_batch).pow(2)
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value_loss = torch.max(value_losses, value_losses_clipped).mean()
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else:
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value_loss = (returns_batch - value_batch).pow(2).mean()
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loss = surrogate_loss + self.value_loss_coef * value_loss - self.entropy_coef * entropy_batch.mean()
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# Gradient step
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self.optimizer.zero_grad()
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loss.backward()
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nn.utils.clip_grad_norm_(self.actor_critic.parameters(), self.max_grad_norm)
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self.optimizer.step()
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mean_value_loss += value_loss.item()
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mean_surrogate_loss += surrogate_loss.item()
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num_updates = self.num_learning_epochs * self.num_mini_batches
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mean_value_loss /= num_updates
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mean_surrogate_loss /= num_updates
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self.storage.clear()
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return mean_value_loss, mean_surrogate_loss
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