intrinsic_motivation_actor_learner.py

# -*- encoding: utf-8 -*-
import time
import cPickle
import numpy as np
import utils.logger
import tensorflow as tf

from skimage.transform import resize
from collections import deque
from utils import checkpoint_utils
from actor_learner import ONE_LIFE_GAMES
from utils.decorators import Experimental
from utils.fast_cts import CTSDensityModel
from utils.replay_memory import ReplayMemory
from policy_based_actor_learner import A3CLearner, A3CLSTMLearner
from value_based_actor_learner import ValueBasedLearner


logger = utils.logger.getLogger('intrinsic_motivation_actor_learner')


class PixelCNNDensityModel(object):
    pass


class PerPixelDensityModel(object):
    """
    Calculates image probability according to per-pixel counts: P(X) = ∏ p(x_ij)
    Mostly here for debugging purposes as CTSDensityModel is much more expressive
    """
    def __init__(self, height=42, width=42, num_bins=8, beta=0.05):
        self.counts = np.zeros((width, height, num_bins))
        self.height = height
        self.width = width
        self.beta = beta
        self.num_bins = num_bins

    def update(self, obs):
        obs = resize(obs, (self.height, self.width), preserve_range=True)
        obs = np.floor((obs*self.num_bins)).astype(np.int32)
        
        log_prob, log_recoding_prob = self._update(obs)
        return self.exploration_bonus(log_prob, log_recoding_prob)

    def _update(self, obs):
        log_prob = 0.0
        log_recoding_prob = 0.0

        for i in range(self.height):
            for j in range(self.height):
                self.counts[i, j, obs[i, j]] += 1

                bin_count = self.counts[i, j, obs[i, j]]
                pixel_mass = self.counts[i, j].sum()
                log_prob += np.log(bin_count / pixel_mass)
                log_recoding_prob += np.log((bin_count + 1) / (pixel_mass + 1))
        
        return log_prob, log_recoding_prob

    def exploration_bonus(self, log_prob, log_recoding_prob):
        recoding_prob = np.exp(log_recoding_prob)
        prob_ratio = np.exp(log_recoding_prob - log_prob)

        pseudocount = (1 - recoding_prob) / np.maximum(prob_ratio - 1, 1e-10)
        return self.beta / np.sqrt(pseudocount + .01)

    def get_state(self):
        return self.num_bins, self.height, self.width, self.beta, self.counts

    def set_state(self, state):
        self.num_bins, self.height, self.width, self.beta, self.counts = state


class DensityModelMixin(object):
    """
    Mixin to provide initialization and synchronization methods for density models
    """
    def _init_density_model(self, args):
        self.density_model_update_steps = 20*args.q_target_update_steps
        self.density_model_update_flags = args.density_model_update_flags

        model_args = {
            'height': args.cts_rescale_dim,
            'width': args.cts_rescale_dim,
            'num_bins': args.cts_bins,
            'beta': args.cts_beta
        }
        if args.density_model == 'cts':
            self.density_model = CTSDensityModel(**model_args)
        else:
            self.density_model = PerPixelDensityModel(**model_args)


    def write_density_model(self):
        logger.info('T{} Writing Pickled Density Model to File...'.format(self.actor_id))
        raw_data = cPickle.dumps(self.density_model.get_state(), protocol=2)
        with self.barrier.counter.lock, open('/tmp/density_model.pkl', 'wb') as f:
            f.write(raw_data)

        for i in xrange(len(self.density_model_update_flags.updated)):
            self.density_model_update_flags.updated[i] = 1

    def read_density_model(self):
        logger.info('T{} Synchronizing Density Model...'.format(self.actor_id))
        with self.barrier.counter.lock, open('/tmp/density_model.pkl', 'rb') as f:
            raw_data = f.read()

        self.density_model.set_state(cPickle.loads(raw_data))


class A3CDensityModelMixin(DensityModelMixin):
    """
    Mixin to share _train method between A3C and A3C-LSTM models
    """
    def _train(self):
        """ Main actor learner loop for advantage actor critic learning. """
        logger.debug("Actor {} resuming at Step {}".format(self.actor_id, 
            self.global_step.value()))
        
        bonuses = deque(maxlen=100)
        while (self.global_step.value() < self.max_global_steps):
            # Sync local learning net with shared mem
            s = self.emulator.get_initial_state()
            self.reset_hidden_state()
            self.local_episode += 1
            episode_over = False
            total_episode_reward = 0.0
            episode_start_step = self.local_step
            
            while not episode_over:
                self.sync_net_with_shared_memory(self.local_network, self.learning_vars)
                self.save_vars()

                rewards = list()
                states  = list()
                actions = list()
                values  = list()
                local_step_start = self.local_step
                self.set_local_lstm_state()

                while self.local_step - local_step_start < self.max_local_steps and not episode_over:
                    # Choose next action and execute it
                    a, readout_v_t, readout_pi_t = self.choose_next_action(s)                    
                    new_s, reward, episode_over = self.emulator.next(a)
                    total_episode_reward += reward
                    
                    # Update density model
                    current_frame = new_s[...,-1]
                    bonus = self.density_model.update(current_frame)
                    bonuses.append(bonus)

                    if self.is_master() and (self.local_step % 400 == 0):
                        bonus_array = np.array(bonuses)
                        logger.debug('π_a={:.4f} / V={:.4f} / Mean Bonus={:.4f} / Max Bonus={:.4f}'.format(
                            readout_pi_t[a.argmax()], readout_v_t, bonus_array.mean(), bonus_array.max()))

                    # Rescale or clip immediate reward
                    reward = self.rescale_reward(self.rescale_reward(reward) + bonus)
                    rewards.append(reward)
                    states.append(s)
                    actions.append(a)
                    values.append(readout_v_t)

                    s = new_s
                    self.local_step += 1

                    global_step, _ = self.global_step.increment()
                    if global_step % self.density_model_update_steps == 0:
                        self.write_density_model()
                    if self.density_model_update_flags.updated[self.actor_id] == 1:
                        self.read_density_model()
                        self.density_model_update_flags.updated[self.actor_id] = 0  
                
                next_val = self.bootstrap_value(new_s, episode_over)
                advantages = self.compute_gae(rewards, values, next_val)
                targets = self.compute_targets(rewards, next_val)
                # Compute gradients on the local policy/V network and apply them to shared memory 
                entropy = self.apply_update(states, actions, targets, advantages)

            elapsed_time = time.time() - self.start_time
            steps_per_sec = self.global_step.value() / elapsed_time
            perf = "{:.0f}".format(steps_per_sec)
            logger.info("T{} / EPISODE {} / STEP {}k / REWARD {} / {} STEPS/s".format(
                self.actor_id,
                self.local_episode,
                self.global_step.value()/1000,
                total_episode_reward,
                perf))

            self.log_summary(total_episode_reward, np.array(values).mean(), entropy)


@Experimental
class PseudoCountA3CLearner(A3CLearner, A3CDensityModelMixin):
    """
    Attempt at replicating the A3C+ model from the paper 'Unifying Count-Based Exploration and Intrinsic Motivation' (https://arxiv.org/abs/1606.01868)
    """
    def __init__(self, args):
        super(PseudoCountA3CLearner, self).__init__(args)
        self._init_density_model(args)

    def train(self):
        self._train()


@Experimental
class PseudoCountA3CLSTMLearner(A3CLSTMLearner, A3CDensityModelMixin):
    def __init__(self, args):
        super(PseudoCountA3CLSTMLearner, self).__init__(args)
        self._init_density_model(args)

    def train(self):
        self._train()


class PseudoCountQLearner(ValueBasedLearner, DensityModelMixin):
    """
    Based on DQN+CTS model from the paper 'Unifying Count-Based Exploration and Intrinsic Motivation' (https://arxiv.org/abs/1606.01868)
    Presently the implementation differs from the paper in that the novelty bonuses are computed online rather than by computing the
    prediction gains after the model has been updated with all frames from the episode. Async training with different final epsilon values
    tends to produce better results than just using a single actor-learner.
    """
    def __init__(self, args):
        self.args = args
        super(PseudoCountQLearner, self).__init__(args)

        self.cts_eta = args.cts_eta
        self.cts_beta = args.cts_beta
        self.batch_size = args.batch_update_size
        self.replay_memory = ReplayMemory(
            args.replay_size,
            self.local_network.get_input_shape(),
            self.num_actions)

        self._init_density_model(args)
        self._double_dqn_op()


    def generate_final_epsilon(self):
        if self.num_actor_learners == 1:
            return self.args.final_epsilon
        else:
            return super(PseudoCountQLearner, self).generate_final_epsilon()


    def _get_summary_vars(self):
        q_vars = super(PseudoCountQLearner, self)._get_summary_vars()

        bonus_q05 = tf.Variable(0., name='novelty_bonus_q05')
        s1 = tf.summary.scalar('Novelty_Bonus_q05_{}'.format(self.actor_id), bonus_q05)
        bonus_q50 = tf.Variable(0., name='novelty_bonus_q50')
        s2 = tf.summary.scalar('Novelty_Bonus_q50_{}'.format(self.actor_id), bonus_q50)
        bonus_q95 = tf.Variable(0., name='novelty_bonus_q95')
        s3 = tf.summary.scalar('Novelty_Bonus_q95_{}'.format(self.actor_id), bonus_q95)

        augmented_reward = tf.Variable(0., name='augmented_episode_reward')
        s4 = tf.summary.scalar('Augmented_Episode_Reward_{}'.format(self.actor_id), augmented_reward)       

        return q_vars + [bonus_q05, bonus_q50, bonus_q95, augmented_reward]


    #TODO: refactor to make this cleaner
    def prepare_state(self, state, total_episode_reward, steps_at_last_reward,
                      ep_t, episode_ave_max_q, episode_over, bonuses, total_augmented_reward):
        # Start a new game on reaching terminal state
        if episode_over:
            T = self.global_step.value() * self.max_local_steps
            t = self.local_step
            e_prog = float(t)/self.epsilon_annealing_steps
            episode_ave_max_q = episode_ave_max_q/float(ep_t)
            s1 = "Q_MAX {0:.4f}".format(episode_ave_max_q)
            s2 = "EPS {0:.4f}".format(self.epsilon)

            self.scores.insert(0, total_episode_reward)
            if len(self.scores) > 100:
                self.scores.pop()

            logger.info('T{0} / STEP {1} / REWARD {2} / {3} / {4}'.format(
                self.actor_id, T, total_episode_reward, s1, s2))
            logger.info('ID: {0} -- RUNNING AVG: {1:.0f} ± {2:.0f} -- BEST: {3:.0f}'.format(
                self.actor_id,
                np.array(self.scores).mean(),
                2*np.array(self.scores).std(),
                max(self.scores),
            ))

            self.log_summary(
                total_episode_reward,
                episode_ave_max_q,
                self.epsilon,
                np.percentile(bonuses, 5),
                np.percentile(bonuses, 50),
                np.percentile(bonuses, 95),
                total_augmented_reward,
            )

            state = self.emulator.get_initial_state()
            ep_t = 0
            total_episode_reward = 0
            episode_ave_max_q = 0
            episode_over = False

        return (
            state,
            total_episode_reward,
            steps_at_last_reward,
            ep_t,
            episode_ave_max_q,
            episode_over
        )


    def _double_dqn_op(self):
        q_local_action = tf.cast(tf.argmax(
            self.local_network.output_layer, axis=1), tf.int32)
        q_target_max = utils.ops.slice_2d(
            self.target_network.output_layer,
            tf.range(0, self.batch_size),
            q_local_action,
        )
        self.one_step_reward = tf.placeholder(tf.float32, self.batch_size, name='one_step_reward')
        self.is_terminal = tf.placeholder(tf.bool, self.batch_size, name='is_terminal')

        self.y_target = self.one_step_reward + self.cts_eta*self.gamma*q_target_max \
            * (1 - tf.cast(self.is_terminal, tf.float32))

        self.double_dqn_loss = self.local_network._value_function_loss(
            self.local_network.q_selected_action
            - tf.stop_gradient(self.y_target))

        self.double_dqn_grads = tf.gradients(self.double_dqn_loss, self.local_network.params)


    # def batch_update(self):
    #     if len(self.replay_memory) < self.replay_memory.maxlen//10:
    #         return

    #     s_i, a_i, r_i, s_f, is_terminal = self.replay_memory.sample_batch(self.batch_size)

    #     feed_dict={
    #         self.one_step_reward: r_i,
    #         self.target_network.input_ph: s_f,
    #         self.local_network.input_ph: np.vstack([s_i, s_f]),
    #         self.local_network.selected_action_ph: np.vstack([a_i, a_i]),
    #         self.is_terminal: is_terminal
    #     }
    #     grads = self.session.run(self.double_dqn_grads, feed_dict=feed_dict)
    #     self.apply_gradients_to_shared_memory_vars(grads)


    def batch_update(self):
        if len(self.replay_memory) < self.replay_memory.maxlen//10:
            return

        s_i, a_i, r_i, s_f, is_terminal = self.replay_memory.sample_batch(self.batch_size)

        feed_dict={
            self.local_network.input_ph: s_f,
            self.target_network.input_ph: s_f,
            self.is_terminal: is_terminal,
            self.one_step_reward: r_i,
        }
        y_target = self.session.run(self.y_target, feed_dict=feed_dict)

        feed_dict={
            self.local_network.input_ph: s_i,
            self.local_network.target_ph: y_target,
            self.local_network.selected_action_ph: a_i
        }
        grads = self.session.run(self.local_network.get_gradients,
                                 feed_dict=feed_dict)
        self.apply_gradients_to_shared_memory_vars(grads)


    def train(self):
        """ Main actor learner loop for n-step Q learning. """
        logger.debug("Actor {} resuming at Step {}, {}".format(self.actor_id, 
            self.global_step.value(), time.ctime()))

        s = self.emulator.get_initial_state()
        
        s_batch = list()
        a_batch = list()
        y_batch = list()
        bonuses = deque(maxlen=1000)
        episode_over = False
        
        t0 = time.time()
        global_steps_at_last_record = self.global_step.value()
        while (self.global_step.value() < self.max_global_steps):
            # # Sync local learning net with shared mem
            # self.sync_net_with_shared_memory(self.local_network, self.learning_vars)
            # self.save_vars()
            rewards =      list()
            states =       list()
            actions =      list()
            max_q_values = list()
            local_step_start = self.local_step
            total_episode_reward = 0
            total_augmented_reward = 0
            episode_ave_max_q = 0
            ep_t = 0

            while not episode_over:
                # Sync local learning net with shared mem
                self.sync_net_with_shared_memory(self.local_network, self.learning_vars)
                self.save_vars()

                # Choose next action and execute it
                a, q_values = self.choose_next_action(s)

                new_s, reward, episode_over = self.emulator.next(a)
                total_episode_reward += reward
                max_q = np.max(q_values)

                current_frame = new_s[...,-1]
                bonus = self.density_model.update(current_frame)
                bonuses.append(bonus)

                # Rescale or clip immediate reward
                reward = self.rescale_reward(self.rescale_reward(reward) + bonus)
                total_augmented_reward += reward
                ep_t += 1
                
                rewards.append(reward)
                states.append(s)
                actions.append(a)
                max_q_values.append(max_q)
                
                s = new_s
                self.local_step += 1
                episode_ave_max_q += max_q
                
                global_step, _ = self.global_step.increment()

                if global_step % self.q_target_update_steps == 0:
                    self.update_target()
                if global_step % self.density_model_update_steps == 0:
                    self.write_density_model()

                # Sync local tensorflow target network params with shared target network params
                if self.target_update_flags.updated[self.actor_id] == 1:
                    self.sync_net_with_shared_memory(self.target_network, self.target_vars)
                    self.target_update_flags.updated[self.actor_id] = 0
                if self.density_model_update_flags.updated[self.actor_id] == 1:
                    self.read_density_model()
                    self.density_model_update_flags.updated[self.actor_id] = 0

                if self.local_step % self.q_update_interval == 0:
                    self.batch_update()

                if self.is_master() and (self.local_step % 500 == 0):
                    bonus_array = np.array(bonuses)
                    steps = global_step - global_steps_at_last_record
                    global_steps_at_last_record = global_step

                    logger.debug('Mean Bonus={:.4f} / Max Bonus={:.4f} / STEPS/s={}'.format(
                        bonus_array.mean(), bonus_array.max(), steps/float(time.time()-t0)))
                    t0 = time.time()


            else:
                #compute monte carlo return
                mc_returns = np.zeros((len(rewards),), dtype=np.float32)
                running_total = 0.0
                for i, r in enumerate(reversed(rewards)):
                    running_total = r + self.gamma*running_total
                    mc_returns[len(rewards)-i-1] = running_total

                mixed_returns = self.cts_eta*np.asarray(rewards) + (1-self.cts_eta)*mc_returns

                #update replay memory
                states.append(new_s)
                episode_length = len(rewards)
                for i in range(episode_length):
                    self.replay_memory.append(
                        states[i],
                        actions[i],
                        mixed_returns[i],
                        i+1 == episode_length)

            s, total_episode_reward, _, ep_t, episode_ave_max_q, episode_over = \
                self.prepare_state(s, total_episode_reward, self.local_step, ep_t, episode_ave_max_q, episode_over, bonuses, total_augmented_reward)