100 lines
3.7 KiB
Python
100 lines
3.7 KiB
Python
import numpy as np
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import torch as T
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from .brain import ActorNetwork, CriticNetwork, PPOMemory
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class Agent:
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def __init__(self, input_dims, n_actions, gamma=0.99, alpha=0.0003,
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policy_clip=0.2, batch_size=64, N=2048, n_epochs=10,
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gae_lambda=0.95, chkpt_dir='tmp/ppo'):
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self.gamma = gamma
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self.policy_clip = policy_clip
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self.n_epochs = n_epochs
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self.gae_lambda = gae_lambda
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self.actor = ActorNetwork(
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input_dims, n_actions, alpha, chkpt_dir=chkpt_dir)
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self.critic = CriticNetwork(
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input_dims, alpha, chkpt_dir=chkpt_dir)
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self.memory = PPOMemory(batch_size)
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def remember(self, state, action, probs, vals, reward, done):
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self.memory.store_memory(state, action, probs, vals, reward, done)
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def save_models(self, actr_chkpt='actor_ppo', crtc_chkpt='critic_ppo'):
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self.actor.save_checkpoint(actr_chkpt)
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self.critic.save_checkpoint(crtc_chkpt)
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def load_models(self, actr_chkpt='actor_ppo', crtc_chkpt='critic_ppo'):
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self.actor.load_checkpoint(actr_chkpt)
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self.critic.load_checkpoint(crtc_chkpt)
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def choose_action(self, observation):
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state = T.tensor(observation, dtype=T.float).to(self.actor.device)
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dist = self.actor(state)
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value = self.critic(state)
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action = dist.sample()
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probs = T.squeeze(dist.log_prob(action)).item()
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action = T.squeeze(action).item()
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value = T.squeeze(value).item()
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return action, probs, value
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def learn(self):
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for _ in range(self.n_epochs):
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state_arr, action_arr, old_probs_arr, vals_arr, reward_arr, dones_arr, batches = self.memory.generate_batches()
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values = vals_arr
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advantage = np.zeros(len(reward_arr), dtype=np.float64)
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for t in range(len(reward_arr)-1):
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discount = 1
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a_t = 0
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for k in range(t, len(reward_arr)-1):
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a_t += discount * \
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(reward_arr[k] + self.gamma*values[k+1]
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* (1-int(dones_arr[k])) - values[k])
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discount *= self.gamma * self.gae_lambda
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advantage[t] = a_t
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advantage = T.tensor(advantage).to(self.actor.device)
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values = T.tensor(values).to(self.actor.device)
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for batch in batches:
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states = T.tensor(state_arr[batch], dtype=T.float).to(
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self.actor.device)
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old_probs = T.tensor(old_probs_arr[batch]).to(
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self.actor.device)
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actions = T.tensor(action_arr[batch]).to(self.actor.device)
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dist = self.actor(states)
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critic_value = self.critic(states)
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critic_value = T.squeeze(critic_value)
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new_probs = dist.log_prob(actions)
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prob_ratio = new_probs.exp() / old_probs.exp()
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weighted_probs = advantage[batch] * prob_ratio
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weighted_clipped_probs = T.clamp(
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prob_ratio, 1-self.policy_clip, 1+self.policy_clip)*advantage[batch]
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self.actor_loss = -T.min(weighted_probs,
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weighted_clipped_probs).mean()
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returns = advantage[batch] + values[batch]
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self.critic_loss = (returns - critic_value)**2
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self.critic_loss = self.critic_loss.mean()
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self.total_loss = self.actor_loss + 0.5*self.critic_loss
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self.actor.optimizer.zero_grad()
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self.critic.optimizer.zero_grad()
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self.total_loss.backward()
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self.actor.optimizer.step()
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self.critic.optimizer.step()
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self.memory.clear_memory()
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