spinup.algos.sac.sac 源代码

import numpy as np
import tensorflow as tf
import gym
import time
from spinup.algos.sac import core
from spinup.algos.sac.core import get_vars
from spinup.utils.logx import EpochLogger

class ReplayBuffer:
    A simple FIFO experience replay buffer for SAC agents.

    def __init__(self, obs_dim, act_dim, size):
        self.obs1_buf = np.zeros([size, obs_dim], dtype=np.float32)
        self.obs2_buf = np.zeros([size, obs_dim], dtype=np.float32)
        self.acts_buf = np.zeros([size, act_dim], dtype=np.float32)
        self.rews_buf = np.zeros(size, dtype=np.float32)
        self.done_buf = np.zeros(size, dtype=np.float32)
        self.ptr, self.size, self.max_size = 0, 0, size

    def store(self, obs, act, rew, next_obs, done):
        self.obs1_buf[self.ptr] = obs
        self.obs2_buf[self.ptr] = next_obs
        self.acts_buf[self.ptr] = act
        self.rews_buf[self.ptr] = rew
        self.done_buf[self.ptr] = done
        self.ptr = (self.ptr+1) % self.max_size
        self.size = min(self.size+1, self.max_size)

    def sample_batch(self, batch_size=32):
        idxs = np.random.randint(0, self.size, size=batch_size)
        return dict(obs1=self.obs1_buf[idxs],


Soft Actor-Critic

(With slight variations that bring it closer to TD3)

[文档]def sac(env_fn, actor_critic=core.mlp_actor_critic, ac_kwargs=dict(), seed=0, steps_per_epoch=5000, epochs=100, replay_size=int(1e6), gamma=0.99, polyak=0.995, lr=1e-3, alpha=0.2, batch_size=100, start_steps=10000, max_ep_len=1000, logger_kwargs=dict(), save_freq=1): """ Args: env_fn : A function which creates a copy of the environment. The environment must satisfy the OpenAI Gym API. actor_critic: A function which takes in placeholder symbols for state, ``x_ph``, and action, ``a_ph``, and returns the main outputs from the agent's Tensorflow computation graph: =========== ================ ====================================== Symbol Shape Description =========== ================ ====================================== ``mu`` (batch, act_dim) | Computes mean actions from policy | given states. ``pi`` (batch, act_dim) | Samples actions from policy given | states. ``logp_pi`` (batch,) | Gives log probability, according to | the policy, of the action sampled by | ``pi``. Critical: must be differentiable | with respect to policy parameters all | the way through action sampling. ``q1`` (batch,) | Gives one estimate of Q* for | states in ``x_ph`` and actions in | ``a_ph``. ``q2`` (batch,) | Gives another estimate of Q* for | states in ``x_ph`` and actions in | ``a_ph``. ``q1_pi`` (batch,) | Gives the composition of ``q1`` and | ``pi`` for states in ``x_ph``: | q1(x, pi(x)). ``q2_pi`` (batch,) | Gives the composition of ``q2`` and | ``pi`` for states in ``x_ph``: | q2(x, pi(x)). ``v`` (batch,) | Gives the value estimate for states | in ``x_ph``. =========== ================ ====================================== ac_kwargs (dict): Any kwargs appropriate for the actor_critic function you provided to SAC. seed (int): Seed for random number generators. steps_per_epoch (int): Number of steps of interaction (state-action pairs) for the agent and the environment in each epoch. epochs (int): Number of epochs to run and train agent. replay_size (int): Maximum length of replay buffer. gamma (float): Discount factor. (Always between 0 and 1.) polyak (float): Interpolation factor in polyak averaging for target networks. Target networks are updated towards main networks according to: .. math:: \\theta_{\\text{targ}} \\leftarrow \\rho \\theta_{\\text{targ}} + (1-\\rho) \\theta where :math:`\\rho` is polyak. (Always between 0 and 1, usually close to 1.) lr (float): Learning rate (used for both policy and value learning). alpha (float): Entropy regularization coefficient. (Equivalent to inverse of reward scale in the original SAC paper.) batch_size (int): Minibatch size for SGD. start_steps (int): Number of steps for uniform-random action selection, before running real policy. Helps exploration. max_ep_len (int): Maximum length of trajectory / episode / rollout. logger_kwargs (dict): Keyword args for EpochLogger. save_freq (int): How often (in terms of gap between epochs) to save the current policy and value function. """ logger = EpochLogger(**logger_kwargs) logger.save_config(locals()) tf.set_random_seed(seed) np.random.seed(seed) env, test_env = env_fn(), env_fn() obs_dim = env.observation_space.shape[0] act_dim = env.action_space.shape[0] # Action limit for clamping: critically, assumes all dimensions share the same bound! act_limit = env.action_space.high[0] # Share information about action space with policy architecture ac_kwargs['action_space'] = env.action_space # Inputs to computation graph x_ph, a_ph, x2_ph, r_ph, d_ph = core.placeholders(obs_dim, act_dim, obs_dim, None, None) # Main outputs from computation graph with tf.variable_scope('main'): mu, pi, logp_pi, q1, q2, q1_pi, q2_pi, v = actor_critic(x_ph, a_ph, **ac_kwargs) # Target value network with tf.variable_scope('target'): _, _, _, _, _, _, _, v_targ = actor_critic(x2_ph, a_ph, **ac_kwargs) # Experience buffer replay_buffer = ReplayBuffer(obs_dim=obs_dim, act_dim=act_dim, size=replay_size) # Count variables var_counts = tuple(core.count_vars(scope) for scope in ['main/pi', 'main/q1', 'main/q2', 'main/v', 'main']) print(('\nNumber of parameters: \t pi: %d, \t' + \ 'q1: %d, \t q2: %d, \t v: %d, \t total: %d\n')%var_counts) # Min Double-Q: min_q_pi = tf.minimum(q1_pi, q2_pi) # Targets for Q and V regression q_backup = tf.stop_gradient(r_ph + gamma*(1-d_ph)*v_targ) v_backup = tf.stop_gradient(min_q_pi - alpha * logp_pi) # Soft actor-critic losses pi_loss = tf.reduce_mean(alpha * logp_pi - q1_pi) q1_loss = 0.5 * tf.reduce_mean((q_backup - q1)**2) q2_loss = 0.5 * tf.reduce_mean((q_backup - q2)**2) v_loss = 0.5 * tf.reduce_mean((v_backup - v)**2) value_loss = q1_loss + q2_loss + v_loss # Policy train op # (has to be separate from value train op, because q1_pi appears in pi_loss) pi_optimizer = tf.train.AdamOptimizer(learning_rate=lr) train_pi_op = pi_optimizer.minimize(pi_loss, var_list=get_vars('main/pi')) # Value train op # (control dep of train_pi_op because sess.run otherwise evaluates in nondeterministic order) value_optimizer = tf.train.AdamOptimizer(learning_rate=lr) value_params = get_vars('main/q') + get_vars('main/v') with tf.control_dependencies([train_pi_op]): train_value_op = value_optimizer.minimize(value_loss, var_list=value_params) # Polyak averaging for target variables # (control flow because sess.run otherwise evaluates in nondeterministic order) with tf.control_dependencies([train_value_op]): target_update = tf.group([tf.assign(v_targ, polyak*v_targ + (1-polyak)*v_main) for v_main, v_targ in zip(get_vars('main'), get_vars('target'))]) # All ops to call during one training step step_ops = [pi_loss, q1_loss, q2_loss, v_loss, q1, q2, v, logp_pi, train_pi_op, train_value_op, target_update] # Initializing targets to match main variables target_init = tf.group([tf.assign(v_targ, v_main) for v_main, v_targ in zip(get_vars('main'), get_vars('target'))]) sess = tf.Session() sess.run(tf.global_variables_initializer()) sess.run(target_init) # Setup model saving logger.setup_tf_saver(sess, inputs={'x': x_ph, 'a': a_ph}, outputs={'mu': mu, 'pi': pi, 'q1': q1, 'q2': q2, 'v': v}) def get_action(o, deterministic=False): act_op = mu if deterministic else pi return sess.run(act_op, feed_dict={x_ph: o.reshape(1,-1)})[0] def test_agent(n=10): global sess, mu, pi, q1, q2, q1_pi, q2_pi for j in range(n): o, r, d, ep_ret, ep_len = test_env.reset(), 0, False, 0, 0 while not(d or (ep_len == max_ep_len)): # Take deterministic actions at test time o, r, d, _ = test_env.step(get_action(o, True)) ep_ret += r ep_len += 1 logger.store(TestEpRet=ep_ret, TestEpLen=ep_len) start_time = time.time() o, r, d, ep_ret, ep_len = env.reset(), 0, False, 0, 0 total_steps = steps_per_epoch * epochs # Main loop: collect experience in env and update/log each epoch for t in range(total_steps): """ Until start_steps have elapsed, randomly sample actions from a uniform distribution for better exploration. Afterwards, use the learned policy. """ if t > start_steps: a = get_action(o) else: a = env.action_space.sample() # Step the env o2, r, d, _ = env.step(a) ep_ret += r ep_len += 1 # Ignore the "done" signal if it comes from hitting the time # horizon (that is, when it's an artificial terminal signal # that isn't based on the agent's state) d = False if ep_len==max_ep_len else d # Store experience to replay buffer replay_buffer.store(o, a, r, o2, d) # Super critical, easy to overlook step: make sure to update # most recent observation! o = o2 if d or (ep_len == max_ep_len): """ Perform all SAC updates at the end of the trajectory. This is a slight difference from the SAC specified in the original paper. """ for j in range(ep_len): batch = replay_buffer.sample_batch(batch_size) feed_dict = {x_ph: batch['obs1'], x2_ph: batch['obs2'], a_ph: batch['acts'], r_ph: batch['rews'], d_ph: batch['done'], } outs = sess.run(step_ops, feed_dict) logger.store(LossPi=outs[0], LossQ1=outs[1], LossQ2=outs[2], LossV=outs[3], Q1Vals=outs[4], Q2Vals=outs[5], VVals=outs[6], LogPi=outs[7]) logger.store(EpRet=ep_ret, EpLen=ep_len) o, r, d, ep_ret, ep_len = env.reset(), 0, False, 0, 0 # End of epoch wrap-up if t > 0 and t % steps_per_epoch == 0: epoch = t // steps_per_epoch # Save model if (epoch % save_freq == 0) or (epoch == epochs-1): logger.save_state({'env': env}, None) # Test the performance of the deterministic version of the agent. test_agent() # Log info about epoch logger.log_tabular('Epoch', epoch) logger.log_tabular('EpRet', with_min_and_max=True) logger.log_tabular('TestEpRet', with_min_and_max=True) logger.log_tabular('EpLen', average_only=True) logger.log_tabular('TestEpLen', average_only=True) logger.log_tabular('TotalEnvInteracts', t) logger.log_tabular('Q1Vals', with_min_and_max=True) logger.log_tabular('Q2Vals', with_min_and_max=True) logger.log_tabular('VVals', with_min_and_max=True) logger.log_tabular('LogPi', with_min_and_max=True) logger.log_tabular('LossPi', average_only=True) logger.log_tabular('LossQ1', average_only=True) logger.log_tabular('LossQ2', average_only=True) logger.log_tabular('LossV', average_only=True) logger.log_tabular('Time', time.time()-start_time) logger.dump_tabular()
if __name__ == '__main__': import argparse parser = argparse.ArgumentParser() parser.add_argument('--env', type=str, default='HalfCheetah-v2') parser.add_argument('--hid', type=int, default=300) parser.add_argument('--l', type=int, default=1) parser.add_argument('--gamma', type=float, default=0.99) parser.add_argument('--seed', '-s', type=int, default=0) parser.add_argument('--epochs', type=int, default=50) parser.add_argument('--exp_name', type=str, default='sac') args = parser.parse_args() from spinup.utils.run_utils import setup_logger_kwargs logger_kwargs = setup_logger_kwargs(args.exp_name, args.seed) sac(lambda : gym.make(args.env), actor_critic=core.mlp_actor_critic, ac_kwargs=dict(hidden_sizes=[args.hid]*args.l), gamma=args.gamma, seed=args.seed, epochs=args.epochs, logger_kwargs=logger_kwargs)