class MADDPG:
def __init__(self, state_size, action_size, num_agents, random_seed):
self.agents = [
DDPG(state_size, action_size, num_agents, random_seed),
DDPG(state_size, action_size, num_agents, random_seed)
]
self.memory = ReplayBuffer(BUFFER_SIZE, BATCH_SIZE, random_seed)
self.num_agents = num_agents
self.state_size = state_size
self.action_size = action_size
self.eps = EPS_START
self.eps_decay = 1 / (EPS_EP_END
) # set decay rate based on epsilon end target
def act(self, states, add_noise=True):
"""Returns actions for given state as per current policy."""
actions = [
agent.act(state, add_noise)
for agent, state in zip(self.agents, states)
]
return actions
def target_act(self, states):
"""Returns actions for given state as per current policy."""
actions = [
agent.target_act(state)
for agent, state in zip(self.agents, states)
]
return actions
def step(self, state, action, reward, next_state, done):
"""Save experience in replay memory, and use random sample from buffer to learn."""
# Save experience / reward
state = np.asanyarray(state)
action = np.asanyarray(action)
reward = np.asanyarray(reward)
next_state = np.asanyarray(next_state)
done = np.asanyarray(done)
self.memory.add(state.reshape((1, self.num_agents, -1)), action.reshape((1, self.num_agents, -1)), \
reward.reshape((1, self.num_agents, -1)), next_state.reshape((1,self.num_agents, -1)), \
done.reshape((1, self.num_agents, -1)))
# Learn, if enough samples are available in memory
if len(self.memory) > BATCH_SIZE:
for ai in range(self.num_agents):
experiences = self.memory.sample()
self.learn(experiences, ai, GAMMA)
def reset(self):
[agent.reset() for agent in self.agents]
def learn(self, experiences, ai, gamma):
"""Update policy and value parameters using given batch of experience tuples.
Q_targets = r + γ * critic_target(next_state, actor_target(next_state))
where:
actor_target(state) -> action
critic_target(state, action) -> Q-value
Params
======
experiences (Tuple[torch.Tensor]): tuple of (s, a, r, s', done) tuples
gamma (float): discount factor
"""
states, actions, rewards, next_states, dones = experiences
agent = self.agents[ai]
# ---------------------------- update critic ---------------------------- #
# Get predicted next-state actions and Q values from target models
next_states = next_states.view(1, BATCH_SIZE, self.num_agents, -1)
actions_next = self.target_act(next_states)
actions_next = torch.cat(actions_next, dim=1)
next_states = next_states.view(BATCH_SIZE, -1)
actions_next = actions_next.view(BATCH_SIZE, -1)
Q_targets_next = agent.critic_target(next_states, actions_next)
# Compute Q targets for current states (y_i)
Q_targets = rewards[:, ai] + (gamma * Q_targets_next *
(1 - dones[:, ai]))
# Compute critic loss
Q_expected = agent.critic_local(states.view(BATCH_SIZE, -1),
actions.view(BATCH_SIZE, -1))
# mean squared error loss
critic_loss = F.mse_loss(Q_expected, Q_targets)
# Minimize the loss
# zero_grad because we do not want to accumulate
# gradients from other batches, so needs to be cleared
agent.critic_optimizer.zero_grad()
# compute derivatives for all variables that
# requires_grad-True
critic_loss.backward()
# update those variables that requires_grad-True
agent.critic_optimizer.step()
# ---------------------------- update actor ---------------------------- #
# Compute actor loss
# take the current states and predict actions
actions_pred = agent.actor_local(states)
#actions_pred = torch.cat(actions_pred, dim=1)
# -1 * (maximize) Q value for the current prediction
actor_loss = -agent.critic_local(states.view(
BATCH_SIZE, -1), actions_pred.view(BATCH_SIZE, -1)).mean()
# Minimize the loss
# zero_grad because we do not want to accumulate
# gradients from other batches, so needs to be cleared
agent.actor_optimizer.zero_grad()
# compute derivatives for all variables that
# requires_grad-True
actor_loss.backward()
# update those variables that requires_grad-True
agent.actor_optimizer.step()
# ----------------------- update target networks ----------------------- #
self.soft_update(agent.critic_local, agent.critic_target, TAU)
self.soft_update(agent.actor_local, agent.actor_target, TAU)
# update noise decay parameter
if self.eps >= EPS_FINAL:
self.eps -= self.eps_decay
self.eps = max(self.eps, EPS_FINAL)
agent.reset()
def soft_update(self, local_model, target_model, tau):
"""Soft update model parameters.
θ_target = τ*θ_local + (1 - τ)*θ_target
Params
======
local_model: PyTorch model (weights will be copied from)
target_model: PyTorch model (weights will be copied to)
tau (float): interpolation parameter
"""
for target_param, local_param in zip(target_model.parameters(),
local_model.parameters()):
target_param.data.copy_(tau * local_param.data +
(1.0 - tau) * target_param.data)
class Agent():
"""Interacts with and learns from the environment."""
def __init__(self,
state_size,
action_size,
random_seed,
memory=None,
buffer_size=BUFFER_SIZE,
batch_size=BATCH_SIZE,
gamma=GAMMA,
tau=TAU,
lr_actor=LR_ACTOR,
lr_critic=LR_CRITIC,
weigth_decay=WEIGHT_DECAY,
pretrained_actor_weights=None,
pretrained_critic_weights=None):
"""Initialize an Agent object.
Params
======
state_size (int): dimension of each state
action_size (int): dimension of each action
random_seed (int): random seed
"""
self.state_size = state_size
self.action_size = action_size
self.seed = random.seed(random_seed)
self.buffer_size = buffer_size
self.batch_size = batch_size
self.gamma = gamma
self.tau = tau
self.lr_actor = lr_actor
self.lr_critic = lr_critic
self.weight_decay = weigth_decay
# Actor Network (w/ Target Network)
self.actor_local = Actor(state_size, action_size,
random_seed).to(device)
self.actor_target = Actor(state_size, action_size,
random_seed).to(device)
self.actor_optimizer = optim.Adam(self.actor_local.parameters(),
lr=self.lr_actor)
# Critic Network (w/ Target Network)
self.critic_local = Critic(state_size, action_size,
random_seed).to(device)
self.critic_target = Critic(state_size, action_size,
random_seed).to(device)
self.critic_optimizer = optim.Adam(self.critic_local.parameters(),
lr=self.lr_critic,
weight_decay=self.weight_decay)
if pretrained_actor_weights:
actor_weights = torch.load(pretrained_actor_weights)
self.actor_local.load_state_dict(actor_weights)
self.actor_target.load_state_dict(actor_weights)
if pretrained_critic_weights:
critic_weights = torch.load(pretrained_critic_weights)
self.critic_local.load_state_dict(critic_weights)
self.critic_target.load_state_dict(critic_weights)
# Noise process
self.noise = OUNoise(action_size, random_seed)
# Replay memory
if memory:
self.memory = memory
else:
self.memory = ReplayBuffer(action_size, self.buffer_size,
self.batch_size, random_seed)
def step(self, state, action, reward, next_state, done):
"""Save experience in replay memory, and use random sample from buffer to learn."""
# Save experience / reward
self.memory.add(state, action, reward, next_state, done)
# Learn, if enough samples are available in memory
if len(self.memory) > self.batch_size:
experiences = self.memory.sample()
self.learn(experiences, self.gamma)
def act(self, state, add_noise=True):
"""Returns actions for given state as per current policy."""
state = torch.from_numpy(state).float().to(device).unsqueeze(0)
self.actor_local.eval()
with torch.no_grad():
action = self.actor_local(state).cpu().data.numpy()
self.actor_local.train()
if add_noise:
action += self.noise.sample()
return np.clip(action, -1, 1)
def reset(self):
self.noise.reset()
def learn(self, experiences, gamma):
"""Update policy and value parameters using given batch of experience tuples.
Q_targets = r + γ * critic_target(next_state, actor_target(next_state))
where:
actor_target(state) -> action
critic_target(state, action) -> Q-value
Params
======
experiences (Tuple[torch.Tensor]): tuple of (s, a, r, s', done) tuples
gamma (float): discount factor
"""
states, actions, rewards, next_states, dones = experiences
# ---------------------------- update critic ---------------------------- #
# Get predicted next-state actions and Q values from target models
actions_next = self.actor_target(next_states)
Q_targets_next = self.critic_target(next_states, actions_next)
# Compute Q targets for current states (y_i)
Q_targets = rewards + (gamma * Q_targets_next * (1 - dones))
# Compute critic loss
Q_expected = self.critic_local(states, actions)
critic_loss = F.mse_loss(Q_expected, Q_targets)
# Minimize the loss
self.critic_optimizer.zero_grad()
critic_loss.backward()
self.critic_optimizer.step()
# ---------------------------- update actor ---------------------------- #
# Compute actor loss
actions_pred = self.actor_local(states)
actor_loss = -self.critic_local(states, actions_pred).mean()
# Minimize the loss
self.actor_optimizer.zero_grad()
actor_loss.backward()
self.actor_optimizer.step()
# ----------------------- update target networks ----------------------- #
self.soft_update(self.critic_local, self.critic_target, self.tau)
self.soft_update(self.actor_local, self.actor_target, self.tau)
self.noise.reset()
def soft_update(self, local_model, target_model, tau):
"""Soft update model parameters.
θ_target = τ*θ_local + (1 - τ)*θ_target
Params
======
local_model: PyTorch model (weights will be copied from)
target_model: PyTorch model (weights will be copied to)
tau (float): interpolation parameter
"""
for target_param, local_param in zip(target_model.parameters(),
local_model.parameters()):
target_param.data.copy_(tau * local_param.data +
(1.0 - tau) * target_param.data)
class Agent():
"""Interacts with and learns from the environment."""
def __init__(self,
state_size,
action_size,
seed,
model='DQN',
buffer_size=int(1e5),
batch_size=64,
gamma=0.99,
tau=1e-3,
lr=5e-4,
update_every=4,
pretrained_model_file=None):
if model not in ('DQN', 'DDQN'):
raise ValueError('Current model supports DQN or DDQN')
"""Initialize an Agent object.
Params
======
state_size (int): dimension of each state
action_size (int): dimension of each action
seed (int): random seed
model (str): currently suports DQN and DDQN
buffer size (int): replay buffer size
batch size (int): minibatch size
gamma (float): discount factor
tau (float): for soft update of target parameters
lr (float): learning rate
update_every (int): how often to update the network
pretrained_model_file (str): filepath to .pth file with pretrained model weights
"""
self.state_size = state_size
self.action_size = action_size
self.seed = random.seed(seed)
self.buffer_size = buffer_size
self.batch_size = batch_size
self.gamma = gamma
self.tau = tau
self.lr = lr
self.update_every = update_every
self.model = model
# Q-Network
self.qnetwork_local = QNetwork(state_size, action_size,
seed).to(device)
self.qnetwork_target = QNetwork(state_size, action_size,
seed).to(device)
self.optimizer = optim.Adam(self.qnetwork_local.parameters(), lr=lr)
if pretrained_model_file:
weights = torch.load(pretrained_model_file)
self.qnetwork_local.load_state_dict(weights)
self.qnetwork_target.load_state_dict(weights)
# Replay memory
self.memory = ReplayBuffer(action_size, buffer_size, batch_size, seed)
# Initialize time step (for updating every UPDATE_EVERY steps)
self.t_step = 0
def step(self, state, action, reward, next_state, done):
# Save experience in replay memory
self.memory.add(state, action, reward, next_state, done)
# Learn every UPDATE_EVERY time steps.
self.t_step = (self.t_step + 1) % self.update_every
if self.t_step == 0:
# If enough samples are available in memory, get random subset and learn
if len(self.memory) > self.batch_size:
experiences = self.memory.sample()
self.learn(experiences)
def act(self, state, eps=0.):
"""Returns actions for given state as per current policy.
Params
======
state (array_like): current state
eps (float): epsilon, for epsilon-greedy action selection
"""
state = torch.from_numpy(state).float().unsqueeze(0).to(device)
self.qnetwork_local.eval()
with torch.no_grad():
action_values = self.qnetwork_local(state)
self.qnetwork_local.train()
# Epsilon-greedy action selection
if random.random() > eps:
return np.argmax(action_values.cpu().data.numpy())
else:
return random.choice(np.arange(self.action_size))
def learn(self, experiences):
"""Update value parameters using given batch of experience tuples.
Params
======
experiences (Tuple[torch.Tensor]): tuple of (s, a, r, s', done) tuples
"""
states, actions, rewards, next_states, dones = experiences
# Get max predicted Q values (for next states) from target model
if self.model == 'DQN':
Q_targets_next = self.qnetwork_target(next_states).detach().max(
1)[0].unsqueeze(1)
if self.model == 'DDQN':
argmax_actions = self.qnetwork_local(next_states).detach().max(
1)[1].unsqueeze(1)
Q_targets_next = self.qnetwork_target(next_states).gather(
1, argmax_actions)
# Compute Q targets for current states
Q_targets = rewards + (self.gamma * Q_targets_next * (1 - dones))
# Get expected Q values from local model
Q_expected = self.qnetwork_local(states).gather(1, actions)
# Compute loss
loss = F.mse_loss(Q_expected, Q_targets)
# Minimize the loss
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
# ------------------- update target network ------------------- #
self.soft_update(self.qnetwork_local, self.qnetwork_target)
def soft_update(self, local_model, target_model):
"""Soft update model parameters.
θ_target = τ*θ_local + (1 - τ)*θ_target
Params
======
local_model (PyTorch model): weights will be copied from
target_model (PyTorch model): weights will be copied to
"""
for target_param, local_param in zip(target_model.parameters(),
local_model.parameters()):
target_param.data.copy_(self.tau * local_param.data +
(1.0 - self.tau) * target_param.data)
class DDPG():
"""Reinforcement Learning agent that learns using DDPG."""
def __init__(self, task):
self.task = task
self.state_size = task.state_size
self.action_size = task.action_size
self.action_low = task.action_low
self.action_high = task.action_high
# Score tracker and learning parameters
self.score = 0
self.best_score = -np.inf
# Actor (Policy) Model
self.actor_local = Actor(self.state_size, self.action_size,
self.action_low, self.action_high)
self.actor_target = Actor(self.state_size, self.action_size,
self.action_low, self.action_high)
# Critic (Value) Model
self.critic_local = Critic(self.state_size, self.action_size)
self.critic_target = Critic(self.state_size, self.action_size)
# Initialize target model parameters with local model parameters
self.critic_target.model.set_weights(
self.critic_local.model.get_weights())
self.actor_target.model.set_weights(
self.actor_local.model.get_weights())
# Noise process
self.exploration_mu = 0.1
self.exploration_theta = 0.3
self.exploration_sigma = 0.3
self.noise = OUNoise(self.action_size, self.exploration_mu,
self.exploration_theta, self.exploration_sigma)
# Replay memory
self.buffer_size = 100000
self.batch_size = 200
self.memory = ReplayBuffer(self.buffer_size, self.batch_size)
# Algorithm parameters
self.gamma = 0.99 # discount factor
self.tau = 0.01 # for soft update of target parameters
def reset_episode(self):
self.total_reward = 0.0
self.count = 0
self.noise.reset()
state = self.task.reset()
self.last_state = state
return state
def step(self, action, reward, next_state, done):
# Save experience / reward
self.total_reward += reward
self.count += 1
self.memory.add(self.last_state, action, reward, next_state, done)
# Learn, if enough samples are available in memory
if len(self.memory) > self.batch_size:
experiences = self.memory.sample()
self.learn(experiences)
# Roll over last state and action
self.last_state = next_state
def act(self, state):
"""Returns actions for given state(s) as per current policy."""
state = np.reshape(state, [-1, self.state_size])
action = self.actor_local.model.predict(state)[0]
return list(action +
self.noise.sample()) # add some noise for exploration
def learn(self, experiences):
"""Update policy and value parameters using given batch of experience tuples."""
self.score = self.total_reward / float(
self.count) if self.count else 0.0
if self.score > self.best_score:
self.best_score = self.score
# Convert experience tuples to separate arrays for each element (states, actions, rewards, etc.)
states = np.vstack([e.state for e in experiences if e is not None])
actions = np.array([e.action for e in experiences
if e is not None]).astype(np.float32).reshape(
-1, self.action_size)
rewards = np.array([e.reward for e in experiences if e is not None
]).astype(np.float32).reshape(-1, 1)
dones = np.array([e.done for e in experiences
if e is not None]).astype(np.uint8).reshape(-1, 1)
next_states = np.vstack(
[e.next_state for e in experiences if e is not None])
# Get predicted next-state actions and Q values from target models
# Q_targets_next = critic_target(next_state, actor_target(next_state))
actions_next = self.actor_target.model.predict_on_batch(next_states)
Q_targets_next = self.critic_target.model.predict_on_batch(
[next_states, actions_next])
# Compute Q targets for current states and train critic model (local)
Q_targets = rewards + self.gamma * Q_targets_next * (1 - dones)
self.critic_local.model.train_on_batch(x=[states, actions],
y=Q_targets)
# Train actor model (local)
action_gradients = np.reshape(
self.critic_local.get_action_gradients([states, actions, 0]),
(-1, self.action_size))
self.actor_local.train_fn([states, action_gradients,
1]) # custom training function
# Soft-update target models
self.soft_update(self.critic_local.model, self.critic_target.model)
self.soft_update(self.actor_local.model, self.actor_target.model)
def soft_update(self, local_model, target_model):
"""Soft update model parameters."""
local_weights = np.array(local_model.get_weights())
target_weights = np.array(target_model.get_weights())
assert len(local_weights) == len(
target_weights
), "Local and target model parameters must have the same size"
new_weights = self.tau * local_weights + (1 -
self.tau) * target_weights
target_model.set_weights(new_weights)
class DDPG_agent():
def __init__(self, state_size, action_size, num_agents, random_seed):
"""init the agent"""
self.state_size = state_size
self.action_size = action_size
self.seed = random_seed
# Construct Actor networks
self.actor_local = Actor(self.state_size, self.action_size, self.seed).to(device)
self.actor_target = Actor(self.state_size, self.action_size, self.seed).to(device)
self.actor_optimizer = optim.Adam(self.actor_local.parameters(), lr=LR_ACTOR)
# Construct Critic networks
self.critic_local = Critic(self.state_size, self.action_size, self.seed).to(device)
self.critic_target = Critic(self.state_size, self.action_size, self.seed).to(device)
self.critic_optimizer = optim.Adam(self.critic_local.parameters(), lr=LR_CRITIC, weight_decay=WEIGHT_DECAY)
# noise processing
self.noise = OUNoise((num_agents,action_size), random_seed)
# Replay memory
self.memory = ReplayBuffer(BUFFER_SIZE, BATCH_SIZE, random_seed)
def act(self, state, add_noise=True):
"""Returns actions for given state as per current policy."""
# convert state from numpy to pytorch array
state = torch.from_numpy(state).float().to(device)
self.actor_local.eval()
with torch.no_grad():
action = self.actor_local(state).cpu().data.numpy()
self.actor_local.train()
if add_noise:
action += self.noise.sample()
return np.clip(action, -1, 1)
def step(self, state, action, reward, next_state, done):
"""Save experience in replay memory, and use random sample from buffer to learn."""
# Save experience / reward
for i in range(state.shape[0]):
self.memory.add(state[i, :], action[i], reward[i], next_state[i, :], done[i])
# Learn, if enough samples are available in memory
if len(self.memory) > BATCH_SIZE:
experiences = self.memory.sample()
self.learn(experiences, GAMMA)
def reset(self):
""" reset noise """
self.noise.reset()
def learn(self, experiences, gamma):
"""Update policy and value parameters using given batch of experience tuples.
Q_targets = r + γ * critic_target(next_state, actor_target(next_state))
where:
actor_target(state) -> action
critic_target(state, action) -> Q-value
Params
======
experiences (Tuple[torch.Tensor]): tuple of (s, a, r, s', done) tuples
gamma (float): discount factor
"""
states, actions, rewards, next_states, dones = experiences
# ---------------------------- update critic ---------------------------- #
# Get predicted next-state actions and Q values from target models
actions_next = self.actor_target(next_states)
Q_targets_next = self.critic_target(next_states, actions_next)
Q_targets = rewards + (gamma * Q_targets_next * (1 - dones))
Q_expected = self.critic_local(states, actions)
critic_loss = F.mse_loss(Q_expected, Q_targets)
self.critic_optimizer.zero_grad()
critic_loss.backward()
self.critic_optimizer.step()
# ---------------------------- update actor ---------------------------- #
# Compute actor loss
actions_pred = self.actor_local(states)
actor_loss = -self.critic_local(states, actions_pred).mean()
self.actor_optimizer.zero_grad()
actor_loss.backward()
self.actor_optimizer.step()
# ----------------------- update target networks ----------------------- #
self.soft_update(self.critic_local, self.critic_target, TAU)
self.soft_update(self.actor_local, self.actor_target, TAU)
def soft_update(self, local_model, target_model, tau):
"""Soft update model parameters.
θ_target = τ*θ_local + (1 - τ)*θ_target
Params
======
local_model: PyTorch model (weights will be copied from)
target_model: PyTorch model (weights will be copied to)
tau (float): interpolation parameter
"""
for target_param, local_param in zip(target_model.parameters(), local_model.parameters()):
target_param.data.copy_(tau*local_param.data + (1.0-tau)*target_param.data)
class DDPG():
"""Reinforcement Learning agent that learns using DDPG."""
def __init__(self, task):
self.task = task
self.state_size = task.state_size
self.action_size = task.action_size
self.action_low = task.action_low
self.action_high = task.action_high
# Actor (Policy) Model
self.actor_local = Actor(self.state_size, self.action_size, self.action_low, self.action_high)
self.actor_target = Actor(self.state_size, self.action_size, self.action_low, self.action_high)
# Critic (Value) Model
self.critic_local = Critic(self.state_size, self.action_size)
self.critic_target = Critic(self.state_size, self.action_size)
# Initialize target model parameters with local model parameters
self.critic_target.model.set_weights(self.critic_local.model.get_weights())
self.actor_target.model.set_weights(self.actor_local.model.get_weights())
# Noise process
self.exploration_mu = 0 #0
self.exploration_theta = 0.15
self.exploration_sigma = 0.2
self.noise = OUNoise(self.action_size, self.exploration_mu, self.exploration_theta, self.exploration_sigma)
# Replay memory
self.buffer_size = 100000
self.batch_size = 64
self.memory = ReplayBuffer(self.buffer_size, self.batch_size)
# Algorithm parameters
self.gamma = 0.99 # discount factor - 0.99
self.tau = 0.01 # for soft update of target parameters - 0.01
# Score tracker and learning parameters
self.best_w = None
self.best_score = -np.inf
self.score = -np.inf
def reset_episode(self):
self.total_reward = 0.0
self.count = 0
self.noise.reset()
state = self.task.reset()
self.last_state = state
return state
def step(self, action, reward, next_state, done):
# Save experience / reward
self.total_reward += reward
self.count += 1
self.memory.add(self.last_state, action, reward, next_state, done)
# Learn, if enough samples are available in memory
if len(self.memory) > self.batch_size:
experiences = self.memory.sample()
self.learn(experiences)
# Roll over last state and action
self.last_state = next_state
def act(self, state):
"""Returns actions for given state(s) as per current policy."""
state = np.reshape(state, [-1, self.state_size])
action = self.actor_local.model.predict(state)[0]
return list(action + self.noise.sample()) # add some noise for exploration
def learn(self, experiences):
"""Update policy and value parameters using given batch of experience tuples."""
self.score = self.total_reward / float(self.count) if self.count else 0.0
if self.score > self.best_score:
self.best_score = self.score
# Convert experience tuples to separate arrays for each element (states, actions, rewards, etc.)
states = np.vstack([e.state for e in experiences if e is not None])
actions = np.array([e.action for e in experiences if e is not None]).astype(np.float32).reshape(-1, self.action_size)
rewards = np.array([e.reward for e in experiences if e is not None]).astype(np.float32).reshape(-1, 1)
dones = np.array([e.done for e in experiences if e is not None]).astype(np.uint8).reshape(-1, 1)
next_states = np.vstack([e.next_state for e in experiences if e is not None])
# Get predicted next-state actions and Q values from target models
# Q_targets_next = critic_target(next_state, actor_target(next_state))
actions_next = self.actor_target.model.predict_on_batch(next_states)
Q_targets_next = self.critic_target.model.predict_on_batch([next_states, actions_next])
# Compute Q targets for current states and train critic model (local)
Q_targets = rewards + self.gamma * Q_targets_next * (1 - dones)
self.critic_local.model.train_on_batch(x=[states, actions], y=Q_targets)
# Train actor model (local)
action_gradients = np.reshape(self.critic_local.get_action_gradients([states, actions, 0]), (-1, self.action_size))
self.actor_local.train_fn([states, action_gradients, 1]) # custom training function
# Soft-update target models
self.soft_update(self.critic_local.model, self.critic_target.model)
self.soft_update(self.actor_local.model, self.actor_target.model)
def soft_update(self, local_model, target_model):
"""Soft update model parameters."""
local_weights = np.array(local_model.get_weights())
target_weights = np.array(target_model.get_weights())
assert len(local_weights) == len(target_weights), "Local and target model parameters must have the same size"
new_weights = self.tau * local_weights + (1 - self.tau) * target_weights
target_model.set_weights(new_weights)
class DDPG():
"""Reinforcement Learning agent that learns using DDPG."""
def __init__(self, task):
# Print debug statements
self.debug = False
# Task (environment) information
self.task = task
self.state_size = task.state_size
self.action_size = task.action_size
self.action_low = task.action_low
self.action_high = task.action_high
self.action_range = self.action_high - self.action_low
# Actor (policy) model
self.actor_lr = 1e-4
self.actor_local = Actor(self.state_size,
self.action_size,
self.action_low,
self.action_high,
learning_rate=self.actor_lr)
self.actor_target = Actor(self.state_size,
self.action_size,
self.action_low,
self.action_high,
learning_rate=self.actor_lr)
# Critic (value) model
self.critic_lr = 1e-4
self.critic_local = Critic(self.state_size,
self.action_size,
learning_rate=self.critic_lr)
self.critic_target = Critic(self.state_size,
self.action_size,
learning_rate=self.critic_lr)
# Print Actor / Critic NN architectures
if self.debug:
self.actor_local.model.summary()
self.critic_local.model.summary()
# Initialize target model parameters with local model parameters
self.critic_target.model.set_weights(
self.critic_local.model.get_weights())
self.actor_target.model.set_weights(
self.actor_local.model.get_weights())
# Noise process
self.exploration_mu = 0
self.exploration_theta = 1.5e-1
self.exploration_sigma = 2.0e-2
self.noise = OUNoise(self.action_size,
mu=self.exploration_mu,
theta=self.exploration_theta,
sigma=self.exploration_sigma)
# Replay memory
self.buffer_size = 100000
self.batch_size = 128
self.memory = ReplayBuffer(self.buffer_size, self.batch_size)
# Algorithm parameters
self.gamma = 0.99 # discount factor
self.tau = 0.001 # for soft update of target parameters
# Score tracker
self.best_score = -np.inf
self.total_reward = 0.0
self.count = 0
# Episode variables
self.reset_episode()
def reset_episode(self):
score = self.total_reward / float(
self.count) if self.count else -np.inf
if score > self.best_score:
self.best_score = score
self.total_reward = 0.0
self.count = 0
self.noise.reset()
state = self.task.reset()
self.last_state = state
return state
def soft_update(self, local_model, target_model):
"""Soft update model parameters."""
local_weights = np.array(local_model.get_weights())
target_weights = np.array(target_model.get_weights())
assert len(local_weights) == len(
target_weights
), "Local and target model parameters must have the same size"
new_weights = self.tau * local_weights + (1 -
self.tau) * target_weights
target_model.set_weights(new_weights)
def step(self, action, reward, next_state, done):
# Save experience / reward
self.memory.add(self.last_state, action, reward, next_state, done)
self.total_reward += reward
self.count += 1
# Learn if enough samples are in memory
if len(self.memory) > self.batch_size:
experiences = self.memory.sample()
self.learn(experiences)
# Roll over last state and action
self.last_state = next_state
def act(self, state):
"""Returns actions for given state(s) as per current policy."""
state = np.reshape(state, [-1, self.state_size])
action = self.actor_local.model.predict(state)[0]
return list(action +
self.noise.sample()) # Add some noise for exploration
def learn(self, experiences):
"""Update policy and value parameters using given batch of experience tuples."""
states = np.vstack([e.state for e in experiences if e is not None])
actions = np.array([e.action for e in experiences
if e is not None]).astype(np.float32).reshape(
-1, self.action_size)
rewards = np.array([e.reward for e in experiences if e is not None
]).astype(np.float32).reshape(-1, 1)
dones = np.array([e.done for e in experiences
if e is not None]).astype(np.uint8).reshape(-1, 1)
next_states = np.vstack(
[e.next_state for e in experiences if e is not None])
# Get predicted next state actions and Q values from target networks
actions_next = self.actor_target.model.predict_on_batch(next_states)
Q_targets_next = self.critic_target.model.predict_on_batch(
[next_states, actions_next])
# Compute Q targets for current states and train critic model (local)
Q_targets = rewards + self.gamma * Q_targets_next * (1 - dones)
self.critic_local.model.train_on_batch(x=[states, actions],
y=Q_targets)
# Train actor model (local)
action_gradients = np.reshape(
self.critic_local.get_action_gradients([states, actions, 0]),
(-1, self.action_size))
self.actor_local.train_fn([states, action_gradients,
1]) # custom training function
# Soft update target models
self.soft_update(self.critic_local.model, self.critic_target.model)
self.soft_update(self.actor_local.model, self.actor_target.model)
