def update(self, transition_dict): states = torch.tensor(transition_dict['states'], dtype=torch.float).to(self.device) actions = torch.tensor(transition_dict['actions']).view(-1, 1).to( self.device) rewards = torch.tensor(transition_dict['rewards'], dtype=torch.float).view(-1, 1).to(self.device) next_states = torch.tensor(transition_dict['next_states'], dtype=torch.float).to(self.device) dones = torch.tensor(transition_dict['dones'], dtype=torch.float).view(-1, 1).to(self.device) q_values = self.q_net(states).gather(1, actions) # Q值 # 下个状态的最大Q值 max_next_q_values = self.target_q_net(next_states).max(1)[0].view( -1, 1) q_targets = rewards + self.gamma * max_next_q_values * (1 - dones ) # TD误差目标 dqn_loss = torch.mean(F.mse_loss(q_values, q_targets)) # 均方误差损失函数 self.optimizer.zero_grad() # PyTorch中默认梯度会累积,这里需要显式将梯度置为0 dqn_loss.backward() # 反向传播更新参数 self.optimizer.step() 解释
时间: 2024-04-16 22:25:18 浏览: 36
这段代码实现了DQN算法的更新步骤。
首先,从transition_dict中获取训练样本的各个部分,包括states(状态)、actions(动作)、rewards(奖励)、next_states(下一个状态)和dones(终止标志)。将它们转换为torch.tensor对象,并将其移动到指定的设备上。
接下来,通过self.q_net调用Q网络,传入states作为输入,并使用gather方法根据actions获取对应的Q值。这里使用gather方法的目的是从Q网络的输出中选择与实际采取的动作相对应的Q值。
然后,通过self.target_q_net调用目标网络,传入next_states作为输入,并使用max方法获取每个下一个状态的最大Q值。这里使用max(1)[0]是为了获取每行的最大值。将得到的最大Q值乘以折扣因子gamma,并与rewards相加得到Q值目标q_targets。
接下来,使用均方误差损失函数(F.mse_loss)计算预测的Q值q_values与目标Q值q_targets之间的均方误差dqn_loss。
在反向传播之前,需要将优化器的梯度置零,以防止梯度累积。然后,调用backward方法进行反向传播计算梯度,并调用optimizer.step()方法更新模型的参数。
这样,通过update方法就可以对DQN算法中的Q网络进行一次更新。
相关问题
帮我给每一行代码添加注释 class DeepKalmanFilter(nn.Module): def __init__(self, config): super(DeepKalmanFilter, self).__init__() self.emitter = Emitter(config.z_dim, config.emit_hidden_dim, config.obs_dim) self.transition = Transition(config.z_dim, config.trans_hidden_dim) self.posterior = Posterior( config.z_dim, config.post_hidden_dim, config.obs_dim ) self.z_q_0 = nn.Parameter(torch.zeros(config.z_dim)) self.emit_log_sigma = nn.Parameter(config.emit_log_sigma * torch.ones(config.obs_dim)) self.config = config @staticmethod def reparametrization(mu, sig): return mu + torch.randn_like(sig) * sig @staticmethod def kl_div(mu0, sig0, mu1, sig1): return -0.5 * torch.sum(1 - 2 * sig1.log() + 2 * sig0.log() - (mu1 - mu0).pow(2) / sig1.pow(2) - (sig0 / sig1).pow(2)) def loss(self, obs): time_step = obs.size(1) batch_size = obs.size(0) overshoot_len = self.config.overshooting kl = torch.Tensor([0]).to(self.config.device) reconstruction = torch.Tensor([0]).to(self.config.device) emit_sig = self.emit_log_sigma.exp() for s in range(self.config.sampling_num): z_q_t = self.z_q_0.expand((batch_size, self.config.z_dim)) for t in range(time_step): trans_loc, trans_sig = self.transition(z_q_t) post_loc, post_sig = self.posterior(trans_loc, trans_sig, obs[:, t]) z_q_t = self.reparametrization(post_loc, post_sig) emit_loc = self.emitter(z_q_t) reconstruction += ((emit_loc - obs[:, t]).pow(2).sum(dim=0) / 2 / emit_sig + self.emit_log_sigma * batch_size / 2).sum() if t > 0: over_loc, over_sig = self.transition(overshooting[:overshoot_len - 1]) over_loc = torch.cat([trans_loc.unsqueeze(0), over_loc], dim=0) over_sig = torch.cat([trans_sig.unsqueeze(0), over_sig], dim=0) else: over_loc = trans_loc.unsqueeze(0) over_sig = trans_sig.unsqueeze(0) overshooting = self.reparametrization(over_loc, over_sig) kl = kl + self.kl_div(post_loc.expand_as(over_loc), post_sig.expand_as(over_sig), over_loc, over_sig) / min(t + 1, self.config.overshooting) reconstruction = reconstruction / self.config.sampling_num kl = kl / self.config.sampling_num return reconstruction, kl
答:class DeepKalmanFilter(nn.Module): # 定义深度Kalman滤波器类
def __init__(self, config): # 初始化
super(DeepKalmanFilter, self).__init__() # 调用父类构造函数
self.emitter = Emitter(config.z_dim, config.emit_hidden_dim, config.obs_dim) # 实例化发射器
self.transition = Transition(config.z_dim, config.trans_hidden_dim) # 实例化转换器
self.posterior = Posterior(config.z_dim, config.post_hidden_dim, config.obs_dim) # 实例化后验概率
self.z_q_0 = nn.Parameter(torch.zeros(config.z_dim)) # 设置参数z_q_0
self.emit_log_sigma = nn.Parameter(config.emit_log_sigma * torch.ones(config.obs_dim)) # 发射标准差参数
self.config = config # 配置参数 @staticmethod
def reparametrization(mu, sig): # 重置参数
return mu + torch.randn_like(sig) * sig # 根据均值和标准差重置参数 @staticmethod
def kl_div(mu0, sig0, mu1, sig1): # 计算KL散度
return -0.5 * torch.sum(1 - 2 * sig1.log() + 2 * sig0.log() - (mu1 - mu0).pow(2) / sig1.pow(2) - (sig0 / sig1).pow(2)) # 计算KL散度 def loss(self, obs): # 损失函数
time_step = obs.size(1) # 观测序列的时间步数
batch_size = obs.size(0) # 批量大小
overshoot_len = self.config.overshooting # 超调量
kl = torch.Tensor([0]).to(self.config.device) # kl散度
reconstruction = torch.Tensor([0]).to(self.config.device) # 构建重构误差
emit_sig = self.emit_log_sigma.exp() # 发射标准差
for s in range(self.config.sampling_num): # 采样次数
z_q_t = self.z_q_0.expand((batch_size, self.config.z_dim)) # 估计量初始化
for t in range(time_step): # 遍历每一时刻
trans_loc, trans_sig = self.transition(z_q_t) # 更新转换器
post_loc, post_sig = self.posterior(trans_loc, trans_sig, obs[:, t]) # 更新后验概率
z_q_t = self.reparametrization(post_loc, post_sig) # 重新参数化
emit_loc = self.emitter(z_q_t) # 计算发射器
reconstruction += ((emit_loc - obs[:, t]).pow(2).sum(dim=0) / 2 / emit_sig +
self.emit_log_sigma * batch_size / 2).sum() # 计算重构误差
if t > 0: # 如果不是第一步
over_loc, over_sig = self.transition(overshooting[:overshoot_len - 1]) # 计算超调量
over_loc = torch.cat([trans_loc.unsqueeze(0), over_loc], dim=0) # 转换器的位置
over_sig = torch.cat([trans_sig.unsqueeze(0), over_sig], dim=0) # 转换器的协方差
else: # 如果是第一步
over_loc = trans_loc.unsqueeze(0) # 转换器的位
use_cuda = torch.cuda.is_available() FloatTensor = torch.cuda.FloatTensor if use_cuda else torch.FloatTensor device = torch.device("cpu") #使用GPU进行训练 from torch.autograd import Variable from replay_buffer import ReplayMemory, Transition # set up matplotlib is_ipython = 'inline' in matplotlib.get_backend() if is_ipython: from IPython import display #plt.ion() use_cuda = torch.cuda.is_available() FloatTensor = torch.cuda.FloatTensor if use_cuda else torch.FloatTensor device = torch.device("cpu")把这段代码改成CPU训练
您可以像这样将上述代码更改为在CPU上进行训练:
```
import torch
from torch.autograd import Variable
from replay_buffer import ReplayMemory, Transition
device = torch.device("cpu") # 使用CPU进行训练
# 设置matplotlib
is_ipython = 'inline' in matplotlib.get_backend()
if is_ipython:
from IPython import display
# 定义FloatTensor
FloatTensor = torch.FloatTensor
# 创建replay buffer
memory = ReplayMemory(10000)
# 将模型和优化器移动到CPU上
model = DQN().to(device)
optimizer = optim.Adam(model.parameters())
# 定义状态转换函数
def state_to_tensor(state):
return FloatTensor([state])
# 训练模型
for i in range(num_episodes):
state = env.reset()
for t in count():
# 获取动作
action = select_action(state)
# 执行动作并获取下一状态、奖励、是否结束
next_state, reward, done, _ = env.step(action.item())
# 转换状态和动作为张量
state_tensor = state_to_tensor(state)
action_tensor = LongTensor([action])
next_state_tensor = state_to_tensor(next_state)
# 存储状态转换
memory.push(state_tensor, action_tensor, next_state_tensor, reward)
# 更新状态
state = next_state
# 训练模型
optimize_model()
if done:
break
```
这里我们将使用CPU进行训练,所以我们将`device`设为`torch.device("cpu")`;将`FloatTensor`设为`torch.FloatTensor`即可。同时,我们还需要将模型和优化器移动到CPU上,可以使用`to`方法将它们移动到CPU上。
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