ray/examples/policy_gradient/reinforce/env.py
Philipp Moritz 555dcf35a2 Add policy gradient example. (#344)
* add policy gradient example

* fix typos

* Minor changes plus some documentation.

* Minor fixes.
2017-03-07 23:42:44 -08:00

45 lines
1.6 KiB
Python

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import gym
import numpy as np
def atari_preprocessor(observation):
"Convert images from (210, 160, 3) to (3, 80, 80) by downsampling."
return (observation[25:-25:2,::2,:][None] - 128.0) / 128.8
def ram_preprocessor(observation):
return (observation - 128.0) / 128.0
class BatchedEnv(object):
"A BatchedEnv holds multiple gym enviroments and performs steps on all of them."
def __init__(self, name, batchsize, preprocessor=None):
self.envs = [gym.make(name) for _ in range(batchsize)]
self.observation_space = self.envs[0].observation_space
self.action_space = self.envs[0].action_space
self.batchsize = batchsize
self.preprocessor = preprocessor if preprocessor else lambda obs: obs[None]
def reset(self):
observations = [self.preprocessor(env.reset()) for env in self.envs]
self.shape = observations[0].shape
self.dones = [False for _ in range(self.batchsize)]
return np.vstack(observations)
def step(self, actions, render=False):
observations = []
rewards = []
for i, action in enumerate(actions):
if self.dones[i]:
observations.append(np.zeros(self.shape))
rewards.append(0.0)
continue
observation, reward, done, info = self.envs[i].step(action)
if render:
self.envs[0].render()
observations.append(self.preprocessor(observation))
rewards.append(reward)
self.dones[i] = done
return np.vstack(observations), np.array(rewards, dtype="float32"), np.array(self.dones)