60 lines
2.9 KiB
Python
60 lines
2.9 KiB
Python
import torch
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import numpy as np
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class A2C:
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def __init__(self,models,memories,cfg):
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self.n_actions = cfg['n_actions']
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self.gamma = cfg['gamma']
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self.device = torch.device(cfg['device'])
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self.memory = memories['ACMemory']
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self.actor = models['Actor'].to(self.device)
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self.critic = models['Critic'].to(self.device)
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self.actor_optim = torch.optim.Adam(self.actor.parameters(), lr=cfg['actor_lr'])
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self.critic_optim = torch.optim.Adam(self.critic.parameters(), lr=cfg['critic_lr'])
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def sample_action(self,state):
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state = torch.tensor(state, device=self.device, dtype=torch.float32).unsqueeze(dim=0)
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dist = self.actor(state)
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value = self.critic(state) # note that 'dist' need require_grad=True
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value = value.detach().numpy().squeeze(0)[0]
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action = np.random.choice(self.n_actions, p=dist.detach().numpy().squeeze(0)) # shape(p=(n_actions,1)
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return action,value,dist
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def predict_action(self,state):
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state = torch.tensor(state, device=self.device, dtype=torch.float32).unsqueeze(dim=0)
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dist = self.actor(state)
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value = self.critic(state) # note that 'dist' need require_grad=True
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value = value.detach().numpy().squeeze(0)[0]
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action = np.random.choice(self.n_actions, p=dist.detach().numpy().squeeze(0)) # shape(p=(n_actions,1)
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return action,value,dist
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def update(self,next_state,entropy):
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value_pool,log_prob_pool,reward_pool = self.memory.sample()
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next_state = torch.tensor(next_state, device=self.device, dtype=torch.float32).unsqueeze(dim=0)
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next_value = self.critic(next_state)
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returns = np.zeros_like(reward_pool)
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for t in reversed(range(len(reward_pool))):
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next_value = reward_pool[t] + self.gamma * next_value # G(s_{t},a{t}) = r_{t+1} + gamma * V(s_{t+1})
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returns[t] = next_value
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returns = torch.tensor(returns, device=self.device)
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value_pool = torch.tensor(value_pool, device=self.device)
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advantages = returns - value_pool
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log_prob_pool = torch.stack(log_prob_pool)
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actor_loss = (-log_prob_pool * advantages).mean()
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critic_loss = 0.5 * advantages.pow(2).mean()
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tot_loss = actor_loss + critic_loss + 0.001 * entropy
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self.actor_optim.zero_grad()
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self.critic_optim.zero_grad()
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tot_loss.backward()
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self.actor_optim.step()
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self.critic_optim.step()
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self.memory.clear()
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def save_model(self, path):
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from pathlib import Path
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# create path
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Path(path).mkdir(parents=True, exist_ok=True)
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torch.save(self.actor.state_dict(), f"{path}/actor_checkpoint.pt")
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torch.save(self.critic.state_dict(), f"{path}/critic_checkpoint.pt")
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def load_model(self, path):
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self.actor.load_state_dict(torch.load(f"{path}/actor_checkpoint.pt"))
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self.critic.load_state_dict(torch.load(f"{path}/critic_checkpoint.pt")) |