写一段强化学习神经网络的pytthon代码
时间: 2023-07-19 21:47:22 浏览: 137
好的,这里是一个简单的强化学习神经网络的Python代码,它使用PyTorch实现DQN算法:
```python
import torch
import torch.nn as nn
import torch.optim as optim
class DQN(nn.Module):
def __init__(self, input_size, hidden_size, output_size):
super(DQN, self).__init__()
self.fc1 = nn.Linear(input_size, hidden_size)
self.fc2 = nn.Linear(hidden_size, hidden_size)
self.fc3 = nn.Linear(hidden_size, output_size)
def forward(self, x):
x = torch.relu(self.fc1(x))
x = torch.relu(self.fc2(x))
x = self.fc3(x)
return x
class Agent(object):
def __init__(self, input_size, hidden_size, output_size, lr):
self.dqn = DQN(input_size, hidden_size, output_size)
self.optimizer = optim.Adam(self.dqn.parameters(), lr=lr)
self.loss_fn = nn.MSELoss()
def act(self, state):
q_values = self.dqn(state)
_, action = torch.max(q_values, 1)
return action.item()
def learn(self, state, action, reward, next_state, done):
self.optimizer.zero_grad()
q_values = self.dqn(state)
q_value = q_values.gather(1, action.unsqueeze(1)).squeeze(1)
next_q_values = self.dqn(next_state)
next_q_value, _ = torch.max(next_q_values, 1)
expected_q_value = reward + 0.99 * next_q_value * (1 - done)
loss = self.loss_fn(q_value, expected_q_value.detach())
loss.backward()
self.optimizer.step()
```
这个代码定义了一个DQN类和一个Agent类。DQN类定义了一个三层的全连接神经网络,用于估计每个可能动作的价值函数。Agent类包含一个DQN对象以及一个优化器和损失函数,用于实现强化学习算法中的学习过程。act方法用于根据当前状态选择一个动作,learn方法用于根据当前状态、动作、奖励、下一个状态和是否结束来更新神经网络的参数,以最大化累积奖励。
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