CleanRL: Advanced PPO#
This tutorial shows how to train PPO agents on Atari environments (Parallel). This is a full training script including CLI, logging and integration with TensorBoard and WandB for experiment tracking.
This tutorial is mirrored from CleanRL’s examples. Full documentation and experiment results can be found at https://docs.cleanrl.dev/rl-algorithms/ppo/#ppo_pettingzoo_ma_ataripy
Environment Setup#
To follow this tutorial, you will need to install the dependencies shown below. It is recommended to use a newly-created virtual environment to avoid dependency conflicts.
pettingzoo[butterfly,atari,testing]>=1.24.0
SuperSuit>=3.9.0
tensorboard>=2.11.2
torch>=1.13.1
Then, install ROMs using AutoROM, or specify the path to your Atari rom using the rom_path argument (see Common Parameters).
Code#
The following code should run without any issues. The comments are designed to help you understand how to use PettingZoo with CleanRL. If you have any questions, please feel free to ask in the Discord server, or create an issue on CleanRL’s GitHub.
"""Advanced training script adapted from CleanRL's repository: https://github.com/vwxyzjn/cleanrl/blob/master/cleanrl/ppo_pettingzoo_ma_atari.py.
This is a full training script including CLI, logging and integration with TensorBoard and WandB for experiment tracking.
Full documentation and experiment results can be found at https://docs.cleanrl.dev/rl-algorithms/ppo/#ppo_pettingzoo_ma_ataripy.
Note: default value for total-timesteps has been changed from 2 million to 8000, for easier testing.
Authors: Costa (https://github.com/vwxyzjn), Elliot (https://github.com/elliottower)
"""
# flake8: noqa
import argparse
import importlib
import os
import random
import time
from distutils.util import strtobool
import gymnasium as gym
import numpy as np
import supersuit as ss
import torch
import torch.nn as nn
import torch.optim as optim
from torch.distributions.categorical import Categorical
from torch.utils.tensorboard import SummaryWriter
def parse_args():
# fmt: off
parser = argparse.ArgumentParser()
parser.add_argument("--exp-name", type=str, default=os.path.basename(__file__).rstrip(".py"),
help="the name of this experiment")
parser.add_argument("--seed", type=int, default=1,
help="seed of the experiment")
parser.add_argument("--torch-deterministic", type=lambda x: bool(strtobool(x)), default=True, nargs="?", const=True,
help="if toggled, `torch.backends.cudnn.deterministic=False`")
parser.add_argument("--cuda", type=lambda x: bool(strtobool(x)), default=True, nargs="?", const=True,
help="if toggled, cuda will be enabled by default")
parser.add_argument("--track", type=lambda x: bool(strtobool(x)), default=False, nargs="?", const=True,
help="if toggled, this experiment will be tracked with Weights and Biases")
parser.add_argument("--wandb-project-name", type=str, default="cleanRL",
help="the wandb's project name")
parser.add_argument("--wandb-entity", type=str, default=None,
help="the entity (team) of wandb's project")
parser.add_argument("--capture-video", type=lambda x: bool(strtobool(x)), default=False, nargs="?", const=True,
help="whether to capture videos of the agent performances (check out `videos` folder)")
# Algorithm specific arguments
parser.add_argument("--env-id", type=str, default="pong_v3",
help="the id of the environment")
parser.add_argument("--total-timesteps", type=int, default=12000, # CleanRL default: 2000000
help="total timesteps of the experiments")
parser.add_argument("--learning-rate", type=float, default=2.5e-4,
help="the learning rate of the optimizer")
parser.add_argument("--num-envs", type=int, default=16,
help="the number of parallel game environments")
parser.add_argument("--num-steps", type=int, default=128,
help="the number of steps to run in each environment per policy rollout")
parser.add_argument("--anneal-lr", type=lambda x: bool(strtobool(x)), default=True, nargs="?", const=True,
help="Toggle learning rate annealing for policy and value networks")
parser.add_argument("--gamma", type=float, default=0.99,
help="the discount factor gamma")
parser.add_argument("--gae-lambda", type=float, default=0.95,
help="the lambda for the general advantage estimation")
parser.add_argument("--num-minibatches", type=int, default=4,
help="the number of mini-batches")
parser.add_argument("--update-epochs", type=int, default=4,
help="the K epochs to update the policy")
parser.add_argument("--norm-adv", type=lambda x: bool(strtobool(x)), default=True, nargs="?", const=True,
help="Toggles advantages normalization")
parser.add_argument("--clip-coef", type=float, default=0.1,
help="the surrogate clipping coefficient")
parser.add_argument("--clip-vloss", type=lambda x: bool(strtobool(x)), default=True, nargs="?", const=True,
help="Toggles whether or not to use a clipped loss for the value function, as per the paper.")
parser.add_argument("--ent-coef", type=float, default=0.01,
help="coefficient of the entropy")
parser.add_argument("--vf-coef", type=float, default=0.5,
help="coefficient of the value function")
parser.add_argument("--max-grad-norm", type=float, default=0.5,
help="the maximum norm for the gradient clipping")
parser.add_argument("--target-kl", type=float, default=None,
help="the target KL divergence threshold")
args = parser.parse_args()
args.batch_size = int(args.num_envs * args.num_steps)
args.minibatch_size = int(args.batch_size // args.num_minibatches)
# fmt: on
return args
def layer_init(layer, std=np.sqrt(2), bias_const=0.0):
torch.nn.init.orthogonal_(layer.weight, std)
torch.nn.init.constant_(layer.bias, bias_const)
return layer
class Agent(nn.Module):
def __init__(self, envs):
super().__init__()
self.network = nn.Sequential(
layer_init(nn.Conv2d(6, 32, 8, stride=4)),
nn.ReLU(),
layer_init(nn.Conv2d(32, 64, 4, stride=2)),
nn.ReLU(),
layer_init(nn.Conv2d(64, 64, 3, stride=1)),
nn.ReLU(),
nn.Flatten(),
layer_init(nn.Linear(64 * 7 * 7, 512)),
nn.ReLU(),
)
self.actor = layer_init(nn.Linear(512, envs.single_action_space.n), std=0.01)
self.critic = layer_init(nn.Linear(512, 1), std=1)
def get_value(self, x):
x = x.clone()
x[:, :, :, [0, 1, 2, 3]] /= 255.0
return self.critic(self.network(x.permute((0, 3, 1, 2))))
def get_action_and_value(self, x, action=None):
x = x.clone()
x[:, :, :, [0, 1, 2, 3]] /= 255.0
hidden = self.network(x.permute((0, 3, 1, 2)))
logits = self.actor(hidden)
probs = Categorical(logits=logits)
if action is None:
action = probs.sample()
return action, probs.log_prob(action), probs.entropy(), self.critic(hidden)
if __name__ == "__main__":
# --num-steps 32 --num-envs 6 --total-timesteps 256
args = parse_args()
print(args)
run_name = f"{args.env_id}__{args.exp_name}__{args.seed}__{int(time.time())}"
if args.track:
import wandb
wandb.init(
project=args.wandb_project_name,
entity=args.wandb_entity,
sync_tensorboard=True,
config=vars(args),
name=run_name,
monitor_gym=True,
save_code=True,
)
writer = SummaryWriter(f"runs/{run_name}")
writer.add_text(
"hyperparameters",
"|param|value|\n|-|-|\n%s"
% ("\n".join([f"|{key}|{value}|" for key, value in vars(args).items()])),
)
# TRY NOT TO MODIFY: seeding
random.seed(args.seed)
np.random.seed(args.seed)
torch.manual_seed(args.seed)
torch.backends.cudnn.deterministic = args.torch_deterministic
device = torch.device("cuda" if torch.cuda.is_available() and args.cuda else "cpu")
# env setup
env = importlib.import_module(f"pettingzoo.atari.{args.env_id}").parallel_env()
env = ss.max_observation_v0(env, 2)
env = ss.frame_skip_v0(env, 4)
env = ss.clip_reward_v0(env, lower_bound=-1, upper_bound=1)
env = ss.color_reduction_v0(env, mode="B")
env = ss.resize_v1(env, x_size=84, y_size=84)
env = ss.frame_stack_v1(env, 4)
env = ss.agent_indicator_v0(env, type_only=False)
env = ss.pettingzoo_env_to_vec_env_v1(env)
envs = ss.concat_vec_envs_v1(
env, args.num_envs // 2, num_cpus=0, base_class="gymnasium"
)
envs.single_observation_space = envs.observation_space
envs.single_action_space = envs.action_space
envs.is_vector_env = True
if args.capture_video:
envs = gym.wrappers.RecordVideo(envs, f"videos/{run_name}")
assert isinstance(
envs.single_action_space, gym.spaces.Discrete
), "only discrete action space is supported"
agent = Agent(envs).to(device)
optimizer = optim.Adam(agent.parameters(), lr=args.learning_rate, eps=1e-5)
# ALGO Logic: Storage setup
obs = torch.zeros(
(args.num_steps, args.num_envs) + envs.single_observation_space.shape
).to(device)
actions = torch.zeros(
(args.num_steps, args.num_envs) + envs.single_action_space.shape
).to(device)
logprobs = torch.zeros((args.num_steps, args.num_envs)).to(device)
rewards = torch.zeros((args.num_steps, args.num_envs)).to(device)
terminations = torch.zeros((args.num_steps, args.num_envs)).to(device)
truncations = torch.zeros((args.num_steps, args.num_envs)).to(device)
values = torch.zeros((args.num_steps, args.num_envs)).to(device)
# TRY NOT TO MODIFY: start the game
global_step = 0
start_time = time.time()
next_obs, info = envs.reset(seed=args.seed)
next_obs = torch.Tensor(next_obs).to(device)
next_termination = torch.zeros(args.num_envs).to(device)
next_truncation = torch.zeros(args.num_envs).to(device)
num_updates = args.total_timesteps // args.batch_size
for update in range(1, num_updates + 1):
# Annealing the rate if instructed to do so.
if args.anneal_lr:
frac = 1.0 - (update - 1.0) / num_updates
lrnow = frac * args.learning_rate
optimizer.param_groups[0]["lr"] = lrnow
for step in range(0, args.num_steps):
global_step += 1 * args.num_envs
obs[step] = next_obs
terminations[step] = next_termination
truncations[step] = next_truncation
# ALGO LOGIC: action logic
with torch.no_grad():
action, logprob, _, value = agent.get_action_and_value(next_obs)
values[step] = value.flatten()
actions[step] = action
logprobs[step] = logprob
# TRY NOT TO MODIFY: execute the game and log data.
next_obs, reward, termination, truncation, info = envs.step(
action.cpu().numpy()
)
rewards[step] = torch.tensor(reward).to(device).view(-1)
next_obs, next_termination, next_truncation = (
torch.Tensor(next_obs).to(device),
torch.Tensor(termination).to(device),
torch.Tensor(truncation).to(device),
)
# TODO: fix this
for idx, item in enumerate(info):
player_idx = idx % 2
if "episode" in item.keys():
print(
f"global_step={global_step}, {player_idx}-episodic_return={item['episode']['r']}"
)
writer.add_scalar(
f"charts/episodic_return-player{player_idx}",
item["episode"]["r"],
global_step,
)
writer.add_scalar(
f"charts/episodic_length-player{player_idx}",
item["episode"]["l"],
global_step,
)
# bootstrap value if not done
with torch.no_grad():
next_value = agent.get_value(next_obs).reshape(1, -1)
advantages = torch.zeros_like(rewards).to(device)
lastgaelam = 0
next_done = torch.maximum(next_termination, next_truncation)
dones = torch.maximum(terminations, truncations)
for t in reversed(range(args.num_steps)):
if t == args.num_steps - 1:
nextnonterminal = 1.0 - next_done
nextvalues = next_value
else:
nextnonterminal = 1.0 - dones[t + 1]
nextvalues = values[t + 1]
delta = (
rewards[t] + args.gamma * nextvalues * nextnonterminal - values[t]
)
advantages[t] = lastgaelam = (
delta + args.gamma * args.gae_lambda * nextnonterminal * lastgaelam
)
returns = advantages + values
# flatten the batch
b_obs = obs.reshape((-1,) + envs.single_observation_space.shape)
b_logprobs = logprobs.reshape(-1)
b_actions = actions.reshape((-1,) + envs.single_action_space.shape)
b_advantages = advantages.reshape(-1)
b_returns = returns.reshape(-1)
b_values = values.reshape(-1)
# Optimizing the policy and value network
b_inds = np.arange(args.batch_size)
clipfracs = []
for epoch in range(args.update_epochs):
np.random.shuffle(b_inds)
for start in range(0, args.batch_size, args.minibatch_size):
end = start + args.minibatch_size
mb_inds = b_inds[start:end]
_, newlogprob, entropy, newvalue = agent.get_action_and_value(
b_obs[mb_inds], b_actions.long()[mb_inds]
)
logratio = newlogprob - b_logprobs[mb_inds]
ratio = logratio.exp()
with torch.no_grad():
# calculate approx_kl http://joschu.net/blog/kl-approx.html
old_approx_kl = (-logratio).mean()
approx_kl = ((ratio - 1) - logratio).mean()
clipfracs += [
((ratio - 1.0).abs() > args.clip_coef).float().mean().item()
]
mb_advantages = b_advantages[mb_inds]
if args.norm_adv:
mb_advantages = (mb_advantages - mb_advantages.mean()) / (
mb_advantages.std() + 1e-8
)
# Policy loss
pg_loss1 = -mb_advantages * ratio
pg_loss2 = -mb_advantages * torch.clamp(
ratio, 1 - args.clip_coef, 1 + args.clip_coef
)
pg_loss = torch.max(pg_loss1, pg_loss2).mean()
# Value loss
newvalue = newvalue.view(-1)
if args.clip_vloss:
v_loss_unclipped = (newvalue - b_returns[mb_inds]) ** 2
v_clipped = b_values[mb_inds] + torch.clamp(
newvalue - b_values[mb_inds],
-args.clip_coef,
args.clip_coef,
)
v_loss_clipped = (v_clipped - b_returns[mb_inds]) ** 2
v_loss_max = torch.max(v_loss_unclipped, v_loss_clipped)
v_loss = 0.5 * v_loss_max.mean()
else:
v_loss = 0.5 * ((newvalue - b_returns[mb_inds]) ** 2).mean()
entropy_loss = entropy.mean()
loss = pg_loss - args.ent_coef * entropy_loss + v_loss * args.vf_coef
optimizer.zero_grad()
loss.backward()
nn.utils.clip_grad_norm_(agent.parameters(), args.max_grad_norm)
optimizer.step()
if args.target_kl is not None:
if approx_kl > args.target_kl:
break
y_pred, y_true = b_values.cpu().numpy(), b_returns.cpu().numpy()
var_y = np.var(y_true)
explained_var = np.nan if var_y == 0 else 1 - np.var(y_true - y_pred) / var_y
# TRY NOT TO MODIFY: record rewards for plotting purposes
writer.add_scalar(
"charts/learning_rate", optimizer.param_groups[0]["lr"], global_step
)
writer.add_scalar("losses/value_loss", v_loss.item(), global_step)
writer.add_scalar("losses/policy_loss", pg_loss.item(), global_step)
writer.add_scalar("losses/entropy", entropy_loss.item(), global_step)
writer.add_scalar("losses/old_approx_kl", old_approx_kl.item(), global_step)
writer.add_scalar("losses/approx_kl", approx_kl.item(), global_step)
writer.add_scalar("losses/clipfrac", np.mean(clipfracs), global_step)
writer.add_scalar("losses/explained_variance", explained_var, global_step)
print("SPS:", int(global_step / (time.time() - start_time)))
writer.add_scalar(
"charts/SPS", int(global_step / (time.time() - start_time)), global_step
)
envs.close()
writer.close()