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import numpy as np
from gym import utils
from gym.envs.mujoco import mujoco_env
class Walker2dEnv(mujoco_env.MujocoEnv, utils.EzPickle):
def __init__(self):
mujoco_env.MujocoEnv.__init__(self, "walker2d.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()
done = not (height > 0.8 and height < 2.0 and
ang > -1.0 and ang < 1.0)
ob = self._get_obs()
return ob, reward, done, {}
def _get_obs(self):
qpos = self.sim.data.qpos
qvel = self.sim.data.qvel
return np.concatenate([qpos[1:], np.clip(qvel, -10, 10)]).ravel()
def reset_model(self):
self.set_state(
self.init_qpos + self.np_random.uniform(low=-.005, high=.005, size=self.model.nq),
self.init_qvel + self.np_random.uniform(low=-.005, high=.005, size=self.model.nv)
)
return self._get_obs()
def viewer_setup(self):
self.viewer.cam.trackbodyid = 2
self.viewer.cam.distance = self.model.stat.extent * 0.5
self.viewer.cam.lookat[2] = 1.15
self.viewer.cam.elevation = -20