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import numpy as np
from gym import utils
from gym.envs.mujoco import mujoco_env
class HopperEnv(mujoco_env.MujocoEnv, utils.EzPickle):
def __init__(self):
mujoco_env.MujocoEnv.__init__(self, 'hopper.xml', 4)
utils.EzPickle.__init__(self)
def step(self, a):
posbefore = self.sim.data.qpos[0]
self.do_simulation(a, self.frame_skip)
posafter, height, ang = self.sim.data.qpos[0:3]
alive_bonus = 1.0
reward = (posafter - posbefore) / self.dt
reward += alive_bonus
reward -= 1e-3 * np.square(a).sum()
s = self.state_vector()
done = not (np.isfinite(s).all() and (np.abs(s[2:]) < 100).all() and
(height > .7) and (abs(ang) < .2))
ob = self._get_obs()
return ob, reward, done, {}
def _get_obs(self):
return np.concatenate([
self.sim.data.qpos.flat[1:],
np.clip(self.sim.data.qvel.flat, -10, 10)
])
def reset_model(self):
qpos = self.init_qpos + self.np_random.uniform(low=-.005, high=.005, size=self.model.nq)
qvel = self.init_qvel + self.np_random.uniform(low=-.005, high=.005, size=self.model.nv)
self.set_state(qpos, qvel)
return self._get_obs()
def viewer_setup(self):
self.viewer.cam.trackbodyid = 2
self.viewer.cam.distance = self.model.stat.extent * 0.75
self.viewer.cam.lookat[2] = 1.15
self.viewer.cam.elevation = -20