315 lines
13 KiB
Python
315 lines
13 KiB
Python
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import argparse
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import os
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import random
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import time
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import gym
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import numpy as np
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import torch
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import torch.nn as nn
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import torch.optim as optim
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from stable_baselines3.common.atari_wrappers import (
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ClipRewardEnv,
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EpisodicLifeEnv,
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FireResetEnv,
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MaxAndSkipEnv,
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NoopResetEnv
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)
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from torch.distributions.categorical import Categorical
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from torch.utils.tensorboard import SummaryWriter
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from tqdm import tqdm
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def get_args():
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parser = argparse.ArgumentParser()
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parser.add_argument('--exp_name', type=str, default=os.path.basename(__file__).rstrip('.py'))
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parser.add_argument('--gym_id', type=str, default='BreakoutNoFrameskip-v4')
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parser.add_argument('--learning_rate', type=float, default=2.5e-4)
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parser.add_argument('--seed', type=int, default=1)
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parser.add_argument('--total_steps', type=int, default=int(1e7))
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parser.add_argument('--use_cuda', type=bool, default=True)
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parser.add_argument('--num_envs', type=int, default=8)
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parser.add_argument('--num_steps', type=int, default=128)
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parser.add_argument('--lr_decay', type=bool, default=True)
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parser.add_argument('--use_gae', type=bool, default=True)
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parser.add_argument('--gae_lambda', type=float, default=0.95)
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parser.add_argument('--gamma', type=float, default=0.99)
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parser.add_argument('--num_mini_batches', type=int, default=4)
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parser.add_argument('--update_epochs', type=int, default=4)
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parser.add_argument('--norm_adv', type=bool, default=True)
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parser.add_argument('--clip_value_loss', type=bool, default=True)
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parser.add_argument('--c_1', type=float, default=1.0)
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parser.add_argument('--c_2', type=float, default=0.01)
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parser.add_argument('--max_grad_norm', type=float, default=0.5)
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parser.add_argument('--clip_epsilon', type=float, default=0.2)
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a = parser.parse_args()
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a.batch_size = int(a.num_envs * a.num_steps)
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a.minibatch_size = int(a.batch_size // a.num_mini_batches)
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return a
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def make_env(gym_id, seed):
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def thunk():
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env = gym.make(gym_id)
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env = gym.wrappers.RecordEpisodeStatistics(env)
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env = NoopResetEnv(env, noop_max=30)
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env = MaxAndSkipEnv(env, skip=4)
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env = EpisodicLifeEnv(env)
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if 'FIRE' in env.unwrapped.get_action_meanings():
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env = FireResetEnv(env)
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env = ClipRewardEnv(env)
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env = gym.wrappers.ResizeObservation(env, (84, 84))
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env = gym.wrappers.GrayScaleObservation(env)
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env = gym.wrappers.FrameStack(env, 4)
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env.seed(seed)
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env.action_space.seed(seed)
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env.observation_space.seed(seed)
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return env
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return thunk
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def layer_init(layer, std=np.sqrt(2), bias_const=0.0):
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torch.nn.init.orthogonal_(layer.weight, std)
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torch.nn.init.constant_(layer.bias, bias_const)
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return layer
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class Agent(nn.Module):
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def __init__(self, e):
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super(Agent, self).__init__()
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self.network = nn.Sequential(
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layer_init(nn.Conv2d(4, 32, 8, stride=4)),
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nn.ReLU(),
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layer_init(nn.Conv2d(32, 64, 4, stride=2)),
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nn.ReLU(),
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layer_init(nn.Conv2d(64, 64, 3, stride=1)),
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nn.ReLU(),
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nn.Flatten(),
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layer_init(nn.Linear(64 * 7 * 7, 512)),
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nn.ReLU(),
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)
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self.actor = layer_init(nn.Linear(512, e.single_action_space.n), std=0.01)
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self.critic = layer_init(nn.Linear(512, 1), std=1)
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def get_value(self, x):
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return self.critic(self.network(x / 255.0))
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def get_action_and_value(self, x, a=None, show_all=False):
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hidden = self.network(x / 255.0)
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log = self.actor(hidden)
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p = Categorical(logits=log)
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if a is None:
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a = p.sample()
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if show_all:
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return a, p.log_prob(a), p.entropy(), self.critic(hidden), p.probs
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return a, p.log_prob(a), p.entropy(), self.critic(hidden)
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def main(env_id, seed):
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args = get_args()
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args.gym_id = env_id
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args.seed = seed
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run_name = (
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'ppo' +
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'_epoch_' + str(args.update_epochs) +
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'_seed_' + str(args.seed)
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)
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# Save training logs
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path_string = str(args.gym_id).split('NoFrameskip')[0] + '/' + run_name
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writer = SummaryWriter(path_string)
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writer.add_text(
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'Hyperparameter',
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'|param|value|\n|-|-|\n%s' % ('\n'.join([f'|{key}|{value}|' for key, value in vars(args).items()])),
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)
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# Random seed
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random.seed(args.seed)
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np.random.seed(args.seed)
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torch.manual_seed(args.seed)
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# Initialize environments
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device = torch.device('cuda' if torch.cuda.is_available() and args.use_cuda else 'cpu')
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envs = gym.vector.SyncVectorEnv(
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[make_env(args.gym_id, args.seed + i) for i in range(args.num_envs)]
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)
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assert isinstance(envs.single_action_space, gym.spaces.Discrete), 'only discrete action space is supported'
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agent = Agent(envs).to(device)
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optimizer = optim.Adam(agent.parameters(), lr=args.learning_rate, eps=1e-5)
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# Initialize buffer
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obs = torch.zeros((args.num_steps, args.num_envs) + envs.single_observation_space.shape).to(device)
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actions = torch.zeros((args.num_steps, args.num_envs) + envs.single_action_space.shape).to(device)
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probs = torch.zeros((args.num_steps, args.num_envs, envs.single_action_space.n)).to(device)
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log_probs = torch.zeros((args.num_steps, args.num_envs)).to(device)
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rewards = torch.zeros((args.num_steps, args.num_envs)).to(device)
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dones = torch.zeros((args.num_steps, args.num_envs)).to(device)
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values = torch.zeros((args.num_steps, args.num_envs)).to(device)
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# Data collection
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global_step = 0
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start_time = time.time()
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next_obs = torch.Tensor(envs.reset()).to(device)
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next_done = torch.zeros(args.num_envs).to(device)
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num_updates = int(args.total_steps // args.batch_size)
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for update in tqdm(range(1, num_updates + 1)):
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# Linear decay of learning rate
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if args.lr_decay:
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frac = 1.0 - (update - 1.0) / num_updates
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lr_now = frac * args.learning_rate
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optimizer.param_groups[0]['lr'] = lr_now
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for step in range(0, args.num_steps):
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global_step += 1 * args.num_envs
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obs[step] = next_obs
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dones[step] = next_done
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# Compute the logarithm of the action probability output by the old policy network
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with torch.no_grad():
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action, log_prob, _, value, prob = agent.get_action_and_value(next_obs, show_all=True)
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values[step] = value.flatten()
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actions[step] = action
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probs[step] = prob
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log_probs[step] = log_prob
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# Update the environments
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next_obs, reward, done, info = envs.step(action.cpu().numpy())
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rewards[step] = torch.tensor(reward).to(device).view(-1)
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next_obs, next_done = torch.Tensor(next_obs).to(device), torch.Tensor(done).to(device)
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for item in info:
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if 'episode' in item.keys():
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writer.add_scalar('charts/episodic_return', item['episode']['r'], global_step)
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break
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# Use GAE (Generalized Advantage Estimation) technique to estimate the advantage function
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with torch.no_grad():
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next_value = agent.get_value(next_obs).reshape(1, -1)
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if args.use_gae:
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advantages = torch.zeros_like(rewards).to(device)
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last_gae_lam = 0
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for t in reversed(range(args.num_steps)):
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if t == args.num_steps - 1:
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next_non_terminal = 1.0 - next_done
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next_values = next_value
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else:
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next_non_terminal = 1.0 - dones[t + 1]
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next_values = values[t + 1]
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delta = rewards[t] + args.gamma * next_values * next_non_terminal - values[t]
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advantages[t] = last_gae_lam = (
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delta + args.gamma * args.gae_lambda * next_non_terminal * last_gae_lam
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)
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returns = advantages + values
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else:
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returns = torch.zeros_like(rewards).to(device)
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for t in reversed(range(args.num_steps)):
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if t == args.num_steps - 1:
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next_non_terminal = 1.0 - next_done
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next_return = next_value
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else:
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next_non_terminal = 1.0 - dones[t + 1]
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next_return = returns[t + 1]
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returns[t] = rewards[t] + args.gamma * next_non_terminal * next_return
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advantages = returns - values
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# ---------------------- We have collected enough data, now let's start training ---------------------- #
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# Flatten each batch
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b_obs = obs.reshape((-1,) + envs.single_observation_space.shape)
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b_probs = probs.reshape((-1, envs.single_action_space.n))
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b_log_probs = log_probs.reshape(-1)
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b_actions = actions.reshape((-1,) + envs.single_action_space.shape)
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b_advantages = advantages.reshape(-1)
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b_returns = returns.reshape(-1)
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b_values = values.reshape(-1)
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# Update the policy network and value network
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b_index = np.arange(args.batch_size)
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for epoch in range(1, args.update_epochs + 1):
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np.random.shuffle(b_index)
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for start in range(0, args.batch_size, args.minibatch_size):
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end = start + args.minibatch_size
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mb_index = b_index[start:end]
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# The latest outputs of the policy network and value network
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_, new_log_prob, entropy, new_value, new_probs = (
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agent.get_action_and_value(b_obs[mb_index], b_actions.long()[mb_index], show_all=True)
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)
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# Compute KL divergence
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d = torch.sum(
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b_probs[mb_index] * torch.log((b_probs[mb_index] + 1e-12) / (new_probs + 1e-12)), 1
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)
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writer.add_scalar('charts/average_kld', d.mean(), global_step)
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writer.add_scalar('others/min_kld', d.min(), global_step)
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writer.add_scalar('others/max_kld', d.max(), global_step)
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log_ratio = new_log_prob - b_log_probs[mb_index]
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ratio = log_ratio.exp()
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# Advantage normalization
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mb_advantages = b_advantages[mb_index]
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if args.norm_adv:
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mb_advantages = (mb_advantages - mb_advantages.mean()) / (mb_advantages.std() + 1e-12)
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# Policy loss
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pg_loss1 = -mb_advantages * ratio
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pg_loss2 = -mb_advantages * torch.clamp(ratio, 1 - args.clip_epsilon, 1 + args.clip_epsilon)
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pg_loss = torch.max(pg_loss1, pg_loss2).mean()
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# Value loss
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new_value = new_value.view(-1)
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if args.clip_value_loss:
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v_loss_un_clipped = (new_value - b_returns[mb_index]) ** 2
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v_clipped = b_values[mb_index] + torch.clamp(
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new_value - b_values[mb_index],
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-args.clip_epsilon,
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args.clip_epsilon,
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)
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v_loss_clipped = (v_clipped - b_returns[mb_index]) ** 2
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v_loss_max = torch.max(v_loss_un_clipped, v_loss_clipped)
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v_loss = 0.5 * v_loss_max.mean()
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else:
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v_loss = 0.5 * ((new_value - b_returns[mb_index]) ** 2).mean()
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# Policy entropy
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entropy_loss = entropy.mean()
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# Total loss
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loss = pg_loss + v_loss * args.c_1 - entropy_loss * args.c_2
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# Save the data during the training process
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writer.add_scalar('losses/value_loss', v_loss.item(), global_step)
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writer.add_scalar('losses/policy_loss', pg_loss.item(), global_step)
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writer.add_scalar('losses/entropy', entropy_loss.item(), global_step)
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writer.add_scalar('losses/delta', torch.abs(ratio - 1).mean().item(), global_step)
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# Update network parameters
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optimizer.zero_grad()
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loss.backward()
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nn.utils.clip_grad_norm_(agent.parameters(), args.max_grad_norm)
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optimizer.step()
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y_pre, y_true = b_values.cpu().numpy(), b_returns.cpu().numpy()
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var_y = np.var(y_true)
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explained_var = np.nan if var_y == 0 else 1 - np.var(y_true - y_pre) / var_y
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# Save the data during the training process
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writer.add_scalar('charts/learning_rate', optimizer.param_groups[0]['lr'], global_step)
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writer.add_scalar('others/explained_variance', explained_var, global_step)
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writer.add_scalar('charts/SPS', int(global_step / (time.time() - start_time)), global_step)
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envs.close()
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writer.close()
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def run():
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for env_id in ['Breakout']:
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for seed in [1, 2, 3]:
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print(env_id + 'NoFrameskip-v4', 'seed:', seed)
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main(env_id + 'NoFrameskip-v4', seed)
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if __name__ == '__main__':
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run()
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