# # Unity ML Agents # ## ML-Agent Learning (PPO) # Contains an implementation of PPO as described [here](https://arxiv.org/abs/1707.06347). import logging import os import numpy as np import tensorflow as tf from trainers.buffer import Buffer from trainers.ppo_models import * from trainers.trainer import UnityTrainerException, Trainer logger = logging.getLogger("unityagents") class PPOTrainer(Trainer): """The PPOTrainer is an implementation of the PPO algorythm.""" def __init__(self, sess, env, brain_name, trainer_parameters, training): """ Responsible for collecting experiences and training PPO model. :param sess: Tensorflow session. :param env: The UnityEnvironment. :param trainer_parameters: The parameters for the trainer (dictionary). :param training: Whether the trainer is set for training. """ self.param_keys = ['batch_size', 'beta', 'buffer_size', 'epsilon', 'gamma', 'hidden_units', 'lambd', 'learning_rate', 'max_steps', 'normalize', 'num_epoch', 'num_layers', 'time_horizon', 'sequence_length', 'summary_freq', 'use_recurrent', 'graph_scope', 'summary_path'] for k in self.param_keys: if k not in trainer_parameters: raise UnityTrainerException("The hyperparameter {0} could not be found for the PPO trainer of " "brain {1}.".format(k, brain_name)) super(PPOTrainer, self).__init__(sess, env, brain_name, trainer_parameters, training) self.use_recurrent = trainer_parameters["use_recurrent"] self.sequence_length = 1 self.m_size = None if self.use_recurrent: self.m_size = env.brains[brain_name].memory_space_size self.sequence_length = trainer_parameters["sequence_length"] if self.use_recurrent: if (self.m_size == 0): raise UnityTrainerException("The memory size for brain {0} is 0 even though the trainer uses recurrent." .format(brain_name)) elif (self.m_size % 4 != 0): raise UnityTrainerException("The memory size for brain {0} is {1} but it must be divisible by 4." .format(brain_name, self.m_size)) self.variable_scope = trainer_parameters['graph_scope'] with tf.variable_scope(self.variable_scope): self.model = create_agent_model(env.brains[brain_name], lr=float(trainer_parameters['learning_rate']), h_size=int(trainer_parameters['hidden_units']), epsilon=float(trainer_parameters['epsilon']), beta=float(trainer_parameters['beta']), max_step=float(trainer_parameters['max_steps']), normalize=trainer_parameters['normalize'], use_recurrent=trainer_parameters['use_recurrent'], num_layers=int(trainer_parameters['num_layers']), m_size=self.m_size) stats = {'cumulative_reward': [], 'episode_length': [], 'value_estimate': [], 'entropy': [], 'value_loss': [], 'policy_loss': [], 'learning_rate': []} self.stats = stats self.training_buffer = Buffer() self.cumulative_rewards = {} self.episode_steps = {} self.is_continuous = (env.brains[brain_name].action_space_type == "continuous") self.use_observations = (env.brains[brain_name].number_observations > 0) self.use_states = (env.brains[brain_name].state_space_size > 0) self.summary_path = trainer_parameters['summary_path'] if not os.path.exists(self.summary_path): os.makedirs(self.summary_path) self.summary_writer = tf.summary.FileWriter(self.summary_path) def __str__(self): return '''Hypermarameters for the PPO Trainer of brain {0}: \n{1}'''.format( self.brain_name, '\n'.join(['\t{0}:\t{1}'.format(x, self.trainer_parameters[x]) for x in self.param_keys])) @property def parameters(self): """ Returns the trainer parameters of the trainer. """ return self.trainer_parameters @property def graph_scope(self): """ Returns the graph scope of the trainer. """ return self.variable_scope @property def get_max_steps(self): """ Returns the maximum number of steps. Is used to know when the trainer should be stopped. :return: The maximum number of steps of the trainer """ return float(self.trainer_parameters['max_steps']) @property def get_step(self): """ Returns the number of steps the trainer has performed :return: the step count of the trainer """ return self.sess.run(self.model.global_step) @property def get_last_reward(self): """ Returns the last reward the trainer has had :return: the new last reward """ return self.sess.run(self.model.last_reward) def increment_step(self): """ Increment the step count of the trainer """ self.sess.run(self.model.increment_step) def update_last_reward(self): """ Updates the last reward """ if len(self.stats['cumulative_reward']) > 0: mean_reward = np.mean(self.stats['cumulative_reward']) self.sess.run(self.model.update_reward, feed_dict={self.model.new_reward: mean_reward}) last_reward = self.sess.run(self.model.last_reward) def running_average(self, data, steps, running_mean, running_variance): """ Computes new running mean and variances. :param data: New piece of data. :param steps: Total number of data so far. :param running_mean: TF op corresponding to stored running mean. :param running_variance: TF op corresponding to stored running variance. :return: New mean and variance values. """ mean, var = self.sess.run([running_mean, running_variance]) current_x = np.mean(data, axis=0) new_mean = mean + (current_x - mean) / (steps + 1) new_variance = var + (current_x - new_mean) * (current_x - mean) return new_mean, new_variance def take_action(self, info): """ Decides actions given state/observation information, and takes them in environment. :param info: Current BrainInfo from environment. :return: a tupple containing action, memories, values and an object to be passed to add experiences """ steps = self.get_step info = info[self.brain_name] epsi = None feed_dict = {self.model.batch_size: len(info.states), self.model.sequence_length: 1} run_list = [self.model.output, self.model.probs, self.model.value, self.model.entropy, self.model.learning_rate] if self.is_continuous: run_list.append(self.model.epsilon) if self.use_observations: for i, _ in enumerate(info.observations): feed_dict[self.model.observation_in[i]] = info.observations[i] if self.use_states: feed_dict[self.model.state_in] = info.states if self.use_recurrent: feed_dict[self.model.memory_in] = info.memories run_list += [self.model.memory_out] if (self.is_training and self.brain.state_space_type == "continuous" and self.use_states and self.trainer_parameters['normalize']): new_mean, new_variance = self.running_average(info.states, steps, self.model.running_mean, self.model.running_variance) feed_dict[self.model.new_mean] = new_mean feed_dict[self.model.new_variance] = new_variance run_list = run_list + [self.model.update_mean, self.model.update_variance] values = self.sess.run(run_list, feed_dict=feed_dict) run_out = dict(zip(run_list, values)) self.stats['value_estimate'].append(run_out[self.model.value].mean()) self.stats['entropy'].append(run_out[self.model.entropy]) self.stats['learning_rate'].append(run_out[self.model.learning_rate]) if self.use_recurrent: return run_out[self.model.output], run_out[self.model.memory_out], run_out[self.model.value], run_out else: return run_out[self.model.output], None, run_out[self.model.value], run_out def add_experiences(self, info, next_info, take_action_outputs): """ Adds experiences to each agent's experience history. :param info: Current BrainInfo. :param next_info: Next BrainInfo. :param take_action_outputs: The outputs of the take action method. """ info = info[self.brain_name] next_info = next_info[self.brain_name] actions = take_action_outputs[self.model.output] epsi = 0 if self.is_continuous: epsi = take_action_outputs[self.model.epsilon] a_dist = take_action_outputs[self.model.probs] value = take_action_outputs[self.model.value] for agent_id in info.agents: if agent_id in next_info.agents: idx = info.agents.index(agent_id) next_idx = next_info.agents.index(agent_id) if not info.local_done[idx]: if self.use_observations: for i, _ in enumerate(info.observations): self.training_buffer[agent_id]['observations%d' % i].append(info.observations[i][idx]) if self.use_states: self.training_buffer[agent_id]['states'].append(info.states[idx]) if self.use_recurrent: self.training_buffer[agent_id]['memory'].append(info.memories[idx]) if self.is_continuous: self.training_buffer[agent_id]['epsilons'].append(epsi[idx]) self.training_buffer[agent_id]['actions'].append(actions[idx]) self.training_buffer[agent_id]['rewards'].append(next_info.rewards[next_idx]) self.training_buffer[agent_id]['action_probs'].append(a_dist[idx]) self.training_buffer[agent_id]['value_estimates'].append(value[idx][0]) if agent_id not in self.cumulative_rewards: self.cumulative_rewards[agent_id] = 0 self.cumulative_rewards[agent_id] += next_info.rewards[next_idx] if agent_id not in self.episode_steps: self.episode_steps[agent_id] = 0 self.episode_steps[agent_id] += 1 def process_experiences(self, info): """ Checks agent histories for processing condition, and processes them as necessary. Processing involves calculating value and advantage targets for model updating step. :param info: Current BrainInfo """ info = info[self.brain_name] for l in range(len(info.agents)): agent_actions = self.training_buffer[info.agents[l]]['actions'] if ((info.local_done[l] or len(agent_actions) > self.trainer_parameters['time_horizon']) and len(agent_actions) > 0): if info.local_done[l]: value_next = 0.0 else: feed_dict = {self.model.batch_size: len(info.states), self.model.sequence_length: 1} if self.use_observations: for i in range(len(info.observations)): feed_dict[self.model.observation_in[i]] = info.observations[i] if self.use_states: feed_dict[self.model.state_in] = info.states if self.use_recurrent: feed_dict[self.model.memory_in] = info.memories value_next = self.sess.run(self.model.value, feed_dict)[l] agent_id = info.agents[l] self.training_buffer[agent_id]['advantages'].set( get_gae( rewards=self.training_buffer[agent_id]['rewards'].get_batch(), value_estimates=self.training_buffer[agent_id]['value_estimates'].get_batch(), value_next=value_next, gamma=self.trainer_parameters['gamma'], lambd=self.trainer_parameters['lambd']) ) self.training_buffer[agent_id]['discounted_returns'].set( \ self.training_buffer[agent_id]['advantages'].get_batch() \ + self.training_buffer[agent_id]['value_estimates'].get_batch()) self.training_buffer.append_update_buffer(agent_id, batch_size=None, training_length=self.sequence_length) self.training_buffer[agent_id].reset_agent() if info.local_done[l]: self.stats['cumulative_reward'].append(self.cumulative_rewards[agent_id]) self.stats['episode_length'].append(self.episode_steps[agent_id]) self.cumulative_rewards[agent_id] = 0 self.episode_steps[agent_id] = 0 def end_episode(self): """ A signal that the Episode has ended. The buffer must be reset. Get only called when the academy resets. """ self.training_buffer.reset_all() for agent_id in self.cumulative_rewards: self.cumulative_rewards[agent_id] = 0 for agent_id in self.episode_steps: self.episode_steps[agent_id] = 0 def is_ready_update(self): """ Returns whether or not the trainer has enough elements to run update model :return: A boolean corresponding to whether or not update_model() can be run """ return len(self.training_buffer.update_buffer['actions']) > self.trainer_parameters['buffer_size'] def update_model(self): """ Uses training_buffer to update model. """ num_epoch = self.trainer_parameters['num_epoch'] batch_size = self.trainer_parameters['batch_size'] total_v, total_p = 0, 0 advantages = self.training_buffer.update_buffer['advantages'].get_batch() self.training_buffer.update_buffer['advantages'].set( (advantages - advantages.mean()) / advantages.std()) for k in range(num_epoch): self.training_buffer.update_buffer.shuffle() for l in range(len(self.training_buffer.update_buffer['actions']) // batch_size): start = l * batch_size end = (l + 1) * batch_size _buffer = self.training_buffer.update_buffer feed_dict = {self.model.batch_size: batch_size, self.model.sequence_length: self.sequence_length, self.model.returns_holder: np.array(_buffer['discounted_returns'][start:end]).reshape( [-1]), self.model.advantage: np.array(_buffer['advantages'][start:end]).reshape([-1, 1]), self.model.old_probs: np.array( _buffer['action_probs'][start:end]).reshape([-1, self.brain.action_space_size])} if self.is_continuous: feed_dict[self.model.epsilon] = np.array( _buffer['epsilons'][start:end]).reshape([-1, self.brain.action_space_size]) else: feed_dict[self.model.action_holder] = np.array( _buffer['actions'][start:end]).reshape([-1]) if self.use_states: if self.brain.state_space_type == "continuous": feed_dict[self.model.state_in] = np.array( _buffer['states'][start:end]).reshape( [-1, self.brain.state_space_size * self.brain.stacked_states]) else: feed_dict[self.model.state_in] = np.array( _buffer['states'][start:end]).reshape([-1, 1]) if self.use_observations: for i, _ in enumerate(self.model.observation_in): _obs = np.array(_buffer['observations%d' % i][start:end]) (_batch, _seq, _w, _h, _c) = _obs.shape feed_dict[self.model.observation_in[i]] = _obs.reshape([-1, _w, _h, _c]) # Memories are zeros if self.use_recurrent: feed_dict[self.model.memory_in] = np.zeros([batch_size, self.m_size]) v_loss, p_loss, _ = self.sess.run([self.model.value_loss, self.model.policy_loss, self.model.update_batch], feed_dict=feed_dict) total_v += v_loss total_p += p_loss self.stats['value_loss'].append(total_v) self.stats['policy_loss'].append(total_p) self.training_buffer.reset_update_buffer() def write_summary(self, lesson_number): """ Saves training statistics to Tensorboard. :param lesson_number: The lesson the trainer is at. """ if (self.get_step % self.trainer_parameters['summary_freq'] == 0 and self.get_step != 0 and self.is_training and self.get_step <= self.get_max_steps): steps = self.get_step if len(self.stats['cumulative_reward']) > 0: mean_reward = np.mean(self.stats['cumulative_reward']) logger.info(" {}: Step: {}. Mean Reward: {:0.3f}. Std of Reward: {:0.3f}." .format(self.brain_name, steps, mean_reward, np.std(self.stats['cumulative_reward']))) summary = tf.Summary() for key in self.stats: if len(self.stats[key]) > 0: stat_mean = float(np.mean(self.stats[key])) summary.value.add(tag='Info/{}'.format(key), simple_value=stat_mean) self.stats[key] = [] summary.value.add(tag='Info/Lesson', simple_value=lesson_number) self.summary_writer.add_summary(summary, steps) self.summary_writer.flush() def discount_rewards(r, gamma=0.99, value_next=0.0): """ Computes discounted sum of future rewards for use in updating value estimate. :param r: List of rewards. :param gamma: Discount factor. :param value_next: T+1 value estimate for returns calculation. :return: discounted sum of future rewards as list. """ discounted_r = np.zeros_like(r) running_add = value_next for t in reversed(range(0, r.size)): running_add = running_add * gamma + r[t] discounted_r[t] = running_add return discounted_r def get_gae(rewards, value_estimates, value_next=0.0, gamma=0.99, lambd=0.95): """ Computes generalized advantage estimate for use in updating policy. :param rewards: list of rewards for time-steps t to T. :param value_next: Value estimate for time-step T+1. :param value_estimates: list of value estimates for time-steps t to T. :param gamma: Discount factor. :param lambd: GAE weighing factor. :return: list of advantage estimates for time-steps t to T. """ value_estimates = np.asarray(value_estimates.tolist() + [value_next]) delta_t = rewards + gamma * value_estimates[1:] - value_estimates[:-1] advantage = discount_rewards(r=delta_t, gamma=gamma * lambd) return advantage