理论基础：
可运行代码：
import numpy as np import torch from torch import nn from torch.utils import data from env import GridWorldEnv from utils import drow_policy class DeepQLearning(object): def __init__(self, env: GridWorldEnv, gamma=0.9): self.env = env self.action_space_size = self.env.num_actions self.state_space_size = self.env.num_states self.gamma = gamma self.policy = np.ones((self.state_space_size, self.action_space_size)) / self.action_space_size self.net = nn.Sequential( nn.Linear(2, 16), nn.ReLU(), nn.Linear(16, self.action_space_size) ) self.target_net = nn.Sequential( nn.Linear(2, 16), nn.ReLU(), nn.Linear(16, self.action_space_size) ) self.target_net.load_state_dict(self.net.state_dict()) self.optimizer = torch.optim.SGD(self.net.parameters(), lr=0.01, momentum=0.9) self.loss = nn.MSELoss() def data_iter(self, episode, batch_size=32, is_train=True): reward = [] state = [] action = [] next_state = [] for s, a, r, next_s in episode: reward.append(r) state.append((s // self.env.size, s % self.env.size)) # 有空间位置 next_state.append((next_s // self.env.size, next_s % self.env.size)) action.append(a) reward = torch.tensor(reward, dtype=torch.float32) state = torch.tensor(state, dtype=torch.float32) next_state = torch.tensor(next_state, dtype=torch.float32) action = torch.tensor(action, dtype=torch.long) data_arrays = (state, action, reward, next_state) dataset = data.TensorDataset(*data_arrays) return data.DataLoader(dataset, batch_size=batch_size, shuffle=is_train, drop_last=False) def solve(self, epochs, update_frep): s = self.env.reset() a = np.random.choice(self.action_space_size, p=self.policy[s]) episodes = [] for _ in range(self.action_space_size * self.state_space_size + 1): episode = self.env.generate_episodes(self.policy, s, a, max_steps=1000) episodes.extend(episode) dataloader = self.data_iter(episodes) step = 0 for epoch in range(epochs): for state, action, reward, next_state in dataloader: step += 1 with torch.no_grad(): q_value = self.target_net(next_state) # [B,N] max_q = q_value.max(dim=1).values y_target = reward + self.gamma * max_q # [B,] y = self.net(state) y_ = y.gather(1, action.unsqueeze(1)).squeeze(1) l = self.loss(y_target, y_) self.optimizer.zero_grad() l.backward() self.optimizer.step() if step % update_frep == 0: self.target_net.load_state_dict(self.net.state_dict()) def get_policy(self): for s in range(self.state_space_size): if s in self.env.terminal: self.policy[s, 4] = 1 break s_t = torch.tensor((s // self.env.size, s % self.env.size), dtype=torch.float32) q_value = self.net(s_t) a = q_value.argmax(dim=0).item() self.policy[s] = 0 self.policy[s, a] = 1 return self.policy if __name__ == '__main__': env = GridWorldEnv( size=5, forbidden=[(1, 2), (3, 3)], terminal=[(4, 4)], r_boundary=-1, r_other=0, r_terminal=1, r_forbidden=-1, r_stay=-0.1 ) # 注意samples要大一点，否则每个state被访问到的概率很小 vi = DeepQLearning(env=env, gamma=0.8) vi.solve(epochs=50, update_frep=20) policy = vi.get_policy() print(policy) drow_policy(policy, env)
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