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87 lines
3.2 KiB
Python
87 lines
3.2 KiB
Python
from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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import tensorflow as tf
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import ray
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from ray.rllib.models.catalog import ModelCatalog
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from ray.rllib.evaluation.postprocessing import compute_advantages
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from ray.rllib.evaluation.tf_policy_graph import TFPolicyGraph
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class PGLoss(object):
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"""Simple policy gradient loss."""
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def __init__(self, action_dist, actions, advantages):
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self.loss = -tf.reduce_mean(action_dist.logp(actions) * advantages)
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class PGPolicyGraph(TFPolicyGraph):
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"""Simple policy gradient example of defining a policy graph."""
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def __init__(self, obs_space, action_space, config):
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config = dict(ray.rllib.agents.pg.pg.DEFAULT_CONFIG, **config)
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self.config = config
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# Setup placeholders
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obs = tf.placeholder(tf.float32, shape=[None] + list(obs_space.shape))
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dist_class, self.logit_dim = ModelCatalog.get_action_dist(
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action_space, self.config["model"])
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prev_actions = ModelCatalog.get_action_placeholder(action_space)
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prev_rewards = tf.placeholder(tf.float32, [None], name="prev_reward")
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# Create the model network and action outputs
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self.model = ModelCatalog.get_model({
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"obs": obs,
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"prev_actions": prev_actions,
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"prev_rewards": prev_rewards
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}, obs_space, self.logit_dim, self.config["model"])
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action_dist = dist_class(self.model.outputs) # logit for each action
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# Setup policy loss
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actions = ModelCatalog.get_action_placeholder(action_space)
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advantages = tf.placeholder(tf.float32, [None], name="adv")
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loss = PGLoss(action_dist, actions, advantages).loss
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# Mapping from sample batch keys to placeholders. These keys will be
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# read from postprocessed sample batches and fed into the specified
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# placeholders during loss computation.
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loss_in = [
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("obs", obs),
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("actions", actions),
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("prev_actions", prev_actions),
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("prev_rewards", prev_rewards),
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("advantages", advantages), # added during postprocessing
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]
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# Initialize TFPolicyGraph
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sess = tf.get_default_session()
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TFPolicyGraph.__init__(
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self,
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obs_space,
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action_space,
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sess,
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obs_input=obs,
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action_sampler=action_dist.sample(),
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loss=loss,
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loss_inputs=loss_in,
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state_inputs=self.model.state_in,
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state_outputs=self.model.state_out,
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prev_action_input=prev_actions,
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prev_reward_input=prev_rewards,
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seq_lens=self.model.seq_lens,
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max_seq_len=config["model"]["max_seq_len"])
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sess.run(tf.global_variables_initializer())
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def postprocess_trajectory(self,
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sample_batch,
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other_agent_batches=None,
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episode=None):
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# This ads the "advantages" column to the sample batch
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return compute_advantages(
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sample_batch, 0.0, self.config["gamma"], use_gae=False)
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def get_initial_state(self):
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return self.model.state_init
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