帮我用Python和pytorch写个DQN算法用来训练PONG
时间: 2024-05-13 17:20:56 浏览: 126
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好的,以下是一个简单的DQN算法用来训练PONG游戏的代码。请注意,这只是一个基本的实现,可以做更多的改进和优化。
首先,我们需要安装必要的库:pytorch和gym。
```python
!pip install torch
!pip install gym
```
接下来,我们将导入所需的库和定义一些超参数。
```python
import random
import numpy as np
import torch
import torch.nn as nn
import torch.optim as optim
import gym
# 超参数
BATCH_SIZE = 32
LEARNING_RATE = 0.0005
EPSILON = 1
EPSILON_DECAY = 0.9995
EPSILON_MIN = 0.01
GAMMA = 0.99
TARGET_UPDATE = 10
MEMORY_SIZE = 1000000
```
现在,我们将定义我们的DQN模型。
```python
class DQN(nn.Module):
def __init__(self, input_dim, output_dim):
super(DQN, self).__init__()
self.fc1 = nn.Linear(input_dim, 128)
self.fc2 = nn.Linear(128, 64)
self.fc3 = nn.Linear(64, output_dim)
def forward(self, x):
x = nn.functional.relu(self.fc1(x))
x = nn.functional.relu(self.fc2(x))
x = self.fc3(x)
return x
```
然后,我们将定义我们的游戏环境和存储经验的经验回放缓冲区。
```python
env = gym.make('Pong-v0')
input_dim = env.observation_space.shape[0] * env.observation_space.shape[1] * env.observation_space.shape[2]
output_dim = env.action_space.n
memory = []
```
接下来,我们将定义我们的DQN代理和目标网络,以及与之关联的优化器。
```python
agent = DQN(input_dim, output_dim)
target = DQN(input_dim, output_dim)
target.load_state_dict(agent.state_dict())
target.eval()
optimizer = optim.Adam(agent.parameters(), lr=LEARNING_RATE)
```
现在,我们将定义我们的动作选择函数,该函数将根据当前的epsilon值使用epsilon-greedy策略选择动作。
```python
def select_action(state, epsilon):
if random.random() < epsilon:
return env.action_space.sample()
else:
with torch.no_grad():
state = torch.from_numpy(state).float().unsqueeze(0)
q_values = agent(state)
return q_values.max(1)[1].item()
```
然后,我们将定义我们的训练函数,该函数将从经验回放缓冲区中随机选择一批经验,并使用它们来更新我们的DQN代理。
```python
def train():
if len(memory) < BATCH_SIZE:
return
transitions = random.sample(memory, BATCH_SIZE)
batch = Transition(*zip(*transitions))
state_batch = torch.from_numpy(np.stack(batch.state)).float()
action_batch = torch.from_numpy(np.array(batch.action)).long()
reward_batch = torch.from_numpy(np.array(batch.reward)).float()
next_state_batch = torch.from_numpy(np.stack(batch.next_state)).float()
done_batch = torch.from_numpy(np.array(batch.done)).float()
q_values = agent(state_batch).gather(1, action_batch.unsqueeze(1)).squeeze(1)
next_q_values = target(next_state_batch).max(1)[0].detach()
expected_q_values = reward_batch + (1 - done_batch) * GAMMA * next_q_values
loss = nn.functional.smooth_l1_loss(q_values, expected_q_values)
optimizer.zero_grad()
loss.backward()
optimizer.step()
```
最后,我们将定义我们的主要训练循环,该循环将在游戏中运行并更新我们的DQN代理和目标网络。
```python
Transition = np.dtype([('state', np.float32, (input_dim,)),
('action', np.int32),
('reward', np.float32),
('next_state', np.float32, (input_dim,)),
('done', np.bool)])
epsilon = EPSILON
state = env.reset()
while True:
action = select_action(state, epsilon)
next_state, reward, done, info = env.step(action)
memory.append((state, action, reward, next_state, done))
if len(memory) > MEMORY_SIZE:
del memory[0]
state = next_state
train()
if done:
state = env.reset()
if env._episode_started_at is not None:
episode_length = info['steps'] - env._episode_started_at
if episode_length > 0:
episode_reward = info['score']
print(f"Episode {len(memory)} - Reward: {episode_reward} - Steps: {episode_length}")
if len(memory) % TARGET_UPDATE == 0:
target.load_state_dict(agent.state_dict())
if epsilon > EPSILON_MIN:
epsilon *= EPSILON_DECAY
epsilon = max(EPSILON_MIN, epsilon)
```
这就是我们的DQN算法的完整实现。您可以将其保存为.py文件并在控制台中运行。在训练过程中,您将看到每个回合的奖励和步骤数。请注意,训练可能需要一段时间,具体取决于您的计算机性能和超参数设置。
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