分析下面的代码,请说明self.policy.state_dict()是怎么来的:import torch import torch.nn as nn from torch.distributions import Categorical import gym # pip install box2d box2d-kengz --user device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu") class Mem
时间: 2023-09-14 15:11:40 浏览: 44
在这段代码中,`self.policy.state_dict()` 是来自于 `nn.Module` 类中的方法。`nn.Module` 类是 PyTorch 中所有神经网络模块的基类,它提供了很多有用的方法和属性,其中包括 `state_dict()` 方法。
`state_dict()` 方法用于返回当前模块的状态字典,它包含了模块中所有可学习参数的名称和对应的张量值。在这个代码片段中,`self.policy` 是一个神经网络模型,它是 `nn.Module` 类的子类,因此可以调用 `state_dict()` 方法来获取模型的状态字典。
具体来说,`self.policy.state_dict()` 返回的是一个字典,其中包含了模型中所有可学习参数的名称和对应的张量值,例如:
```python
{
'conv1.weight': tensor([...]),
'conv1.bias': tensor([...]),
'fc1.weight': tensor([...]),
'fc1.bias': tensor([...]),
...
}
```
这个字典中的每一项都是一个键值对,其中键是参数的名称,值是参数的张量值。这个字典可以用于保存模型的参数或者加载模型的参数。
相关问题
请给我使用 PyTorch 实现 DQN 算法来玩 Pong 游戏的完整代码
好的,这是一个使用 PyTorch 实现 DQN 算法来玩 Pong 游戏的完整代码,你可以参考它:
```python
import gym
import torch
import torch.nn as nn
import torch.optim as optim
import torch.nn.functional as F
import random
import numpy as np
from collections import deque
# 设置超参数
BATCH_SIZE = 32
GAMMA = 0.99
EPS_START = 1
EPS_END = 0.02
EPS_DECAY = 1000000
TARGET_UPDATE = 1000
MEMORY_CAPACITY = 100000
LR = 1e-4
ENV_NAME = "Pong-v0"
# 设置环境
env = gym.make(ENV_NAME)
n_actions = env.action_space.n
# 设置设备
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
# 定义神经网络
class DQN(nn.Module):
def __init__(self):
super(DQN, self).__init__()
self.conv1 = nn.Conv2d(4, 32, kernel_size=8, stride=4)
self.conv2 = nn.Conv2d(32, 64, kernel_size=4, stride=2)
self.conv3 = nn.Conv2d(64, 64, kernel_size=3, stride=1)
self.fc1 = nn.Linear(7 * 7 * 64, 512)
self.fc2 = nn.Linear(512, n_actions)
def forward(self, x):
x = F.relu(self.conv1(x))
x = F.relu(self.conv2(x))
x = F.relu(self.conv3(x))
x = x.view(x.size(0), -1)
x = F.relu(self.fc1(x))
x = self.fc2(x)
return x
# 定义经验回放类
class ReplayMemory(object):
def __init__(self, capacity):
self.capacity = capacity
self.memory = deque(maxlen=capacity)
def push(self, state, action, reward, next_state, done):
self.memory.append((state, action, reward, next_state, done))
def sample(self, batch_size):
batch = random.sample(self.memory, batch_size)
state, action, reward, next_state, done = zip(*batch)
return state, action, reward, next_state, done
def __len__(self):
return len(self.memory)
# 定义 DQN 算法类
class DQNAgent(object):
def __init__(self):
self.policy_net = DQN().to(device)
self.target_net = DQN().to(device)
self.target_net.load_state_dict(self.policy_net.state_dict())
self.target_net.eval()
self.optimizer = optim.Adam(self.policy_net.parameters(), lr=LR)
self.memory = ReplayMemory(MEMORY_CAPACITY)
self.steps_done = 0
self.episode_durations = []
self.episode_rewards = []
def select_action(self, state):
sample = random.random()
eps_threshold = EPS_END + (EPS_START - EPS_END) * \
np.exp(-1. * self.steps_done / EPS_DECAY)
self.steps_done += 1
if sample > eps_threshold:
with torch.no_grad():
state = torch.FloatTensor(state).unsqueeze(0).to(device)
q_value = self.policy_net(state)
action = q_value.max(1)[1].view(1, 1)
else:
action = torch.tensor([[random.randrange(n_actions)]], device=device, dtype=torch.long)
return action
def optimize_model(self):
if len(self.memory) < BATCH_SIZE:
return
state, action, reward, next_state, done = self.memory.sample(BATCH_SIZE)
state_batch = torch.FloatTensor(state).to(device)
action_batch = torch.LongTensor(action).unsqueeze(1).to(device)
reward_batch = torch.FloatTensor(reward).to(device)
next_state_batch = torch.FloatTensor(next_state).to(device)
done_batch = torch.FloatTensor(done).to(device)
q_values = self.policy_net(state_batch).gather(1, action_batch)
next_q_values = torch.zeros(BATCH_SIZE, device=device)
next_q_values[~done_batch] = self.target_net(next_state_batch[~done_batch]).max(1)[0].detach()
expected_q_values = (next_q_values * GAMMA) + reward_batch
loss = F.smooth_l1_loss(q_values, expected_q_values.unsqueeze(1))
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
def train(self, num_episodes):
for i_episode in range(num_episodes):
state = env.reset()
state = np.stack((state, state, state, state), axis=0)
episode_reward = 0
for t in range(10000):
action = agent.select_action(state)
next_state, reward, done, _ = env.step(action.item())
episode_reward += reward
next_state = np.append(np.expand_dims(next_state, 0), state[:3, :, :], axis=0)
agent.memory.push(state, action.item(), reward, next_state, done)
state = next_state
agent.optimize_model()
if done:
agent.episode_durations.append(t + 1)
agent.episode_rewards.append(episode_reward)
if i_episode % 10 == 0:
print("Episode: {}, Reward: {}".format(i_episode, episode_reward))
break
if i_episode % TARGET_UPDATE == 0:
agent.target_net.load_state_dict(agent.policy_net.state_dict())
env.close()
if __name__ == "__main__":
agent = DQNAgent()
agent.train(1000)
```
注意:这段代码需要安装 gym 和 PyTorch 库。在运行代码之前,请确保你已经按照这些库。
请为我提供一个用pytorch写的DQN代码
以下是一个使用 PyTorch 编写的 DQN 代码示例:
```python
import torch
import torch.nn as nn
import torch.optim as optim
import torch.nn.functional as F
import numpy as np
import random
from collections import deque
class DQN(nn.Module):
def __init__(self, state_dim, action_dim):
super(DQN, self).__init__()
self.fc1 = nn.Linear(state_dim, 64)
self.fc2 = nn.Linear(64, 64)
self.fc3 = nn.Linear(64, action_dim)
def forward(self, x):
x = F.relu(self.fc1(x))
x = F.relu(self.fc2(x))
x = self.fc3(x)
return x
class ReplayBuffer:
def __init__(self, capacity):
self.buffer = deque(maxlen=capacity)
def push(self, state, action, reward, next_state, done):
self.buffer.append((state, action, reward, next_state, done))
def sample(self, batch_size):
state, action, reward, next_state, done = zip(*random.sample(self.buffer, batch_size))
return np.array(state), np.array(action), np.array(reward), np.array(next_state), np.array(done)
def __len__(self):
return len(self.buffer)
class Agent:
def __init__(self, state_dim, action_dim, capacity, batch_size, gamma, eps_start, eps_end, eps_decay):
self.device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
self.policy_net = DQN(state_dim, action_dim).to(self.device)
self.target_net = DQN(state_dim, action_dim).to(self.device)
self.target_net.load_state_dict(self.policy_net.state_dict())
self.target_net.eval()
self.optimizer = optim.Adam(self.policy_net.parameters(), lr=.001)
self.memory = ReplayBuffer(capacity)
self.batch_size = batch_size
self.gamma = gamma
self.eps_start = eps_start
self.eps_end = eps_end
self.eps_decay = eps_decay
self.steps_done =
def select_action(self, state):
eps_threshold = self.eps_end + (self.eps_start - self.eps_end) * \
np.exp(-1. * self.steps_done / self.eps_decay)
self.steps_done += 1
if random.random() > eps_threshold:
with torch.no_grad():
state = torch.FloatTensor(state).to(self.device)
q_values = self.policy_net(state)
action = q_values.max()[1].item()
else:
action = random.randrange(2)
return action
def optimize_model(self):
if len(self.memory) < self.batch_size:
return
state, action, reward, next_state, done = self.memory.sample(self.batch_size)
state = torch.FloatTensor(state).to(self.device)
action = torch.LongTensor(action).to(self.device)
reward = torch.FloatTensor(reward).to(self.device)
next_state = torch.FloatTensor(next_state).to(self.device)
done = torch.FloatTensor(done).to(self.device)
q_values = self.policy_net(state).gather(1, action.unsqueeze(1)).squeeze(1)
next_q_values = self.target_net(next_state).max(1)[]
expected_q_values = reward + (1 - done) * self.gamma * next_q_values
loss = F.smooth_l1_loss(q_values, expected_q_values.detach())
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
def update_target_model(self):
self.target_net.load_state_dict(self.policy_net.state_dict())
env = gym.make('CartPole-v')
agent = Agent(state_dim=env.observation_space.shape[], action_dim=env.action_space.n, capacity=10000, batch_size=32, gamma=.99, eps_start=1., eps_end=.01, eps_decay=500)
num_episodes = 100
for i_episode in range(num_episodes):
state = env.reset()
for t in range(100):
action = agent.select_action(state)
next_state, reward, done, _ = env.step(action)
agent.memory.push(state, action, reward, next_state, done)
state = next_state
agent.optimize_model()
if done:
break
if i_episode % 10 == :
agent.update_target_model()
```