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import gym
from gym import spaces
from gym.utils import seeding
import numpy as np
from os import path
class PendulumEnv(gym.Env):
metadata = {
'render.modes' : ['human', 'rgb_array'],
'video.frames_per_second' : 30
}
def __init__(self):
self.max_speed=8
self.max_torque=2.
self.dt=.05
self.viewer = None
high = np.array([1., 1., self.max_speed])
self.action_space = spaces.Box(low=-self.max_torque, high=self.max_torque, shape=(1,), dtype=np.float32)
self.observation_space = spaces.Box(low=-high, high=high, dtype=np.float32)
self.seed()
def seed(self, seed=None):
self.np_random, seed = seeding.np_random(seed)
return [seed]
def step(self,u):
th, thdot = self.state # th := theta
g = 10.
m = 1.
l = 1.
dt = self.dt
u = np.clip(u, -self.max_torque, self.max_torque)[0]
self.last_u = u # for rendering
costs = angle_normalize(th)**2 + .1*thdot**2 + .001*(u**2)
newthdot = thdot + (-3*g/(2*l) * np.sin(th + np.pi) + 3./(m*l**2)*u) * dt
newth = th + newthdot*dt
newthdot = np.clip(newthdot, -self.max_speed, self.max_speed) #pylint: disable=E1111
self.state = np.array([newth, newthdot])
return self._get_obs(), -costs, False, {}
def reset(self):
high = np.array([np.pi, 1])
self.state = self.np_random.uniform(low=-high, high=high)
self.last_u = None
return self._get_obs()
def _get_obs(self):
theta, thetadot = self.state
return np.array([np.cos(theta), np.sin(theta), thetadot])
def render(self, mode='human'):
if self.viewer is None:
from gym.envs.classic_control import rendering
self.viewer = rendering.Viewer(500,500)
self.viewer.set_bounds(-2.2,2.2,-2.2,2.2)
rod = rendering.make_capsule(1, .2)
rod.set_color(.8, .3, .3)
self.pole_transform = rendering.Transform()
rod.add_attr(self.pole_transform)
self.viewer.add_geom(rod)
axle = rendering.make_circle(.05)
axle.set_color(0,0,0)
self.viewer.add_geom(axle)
fname = path.join(path.dirname(__file__), "assets/clockwise.png")
self.img = rendering.Image(fname, 1., 1.)
self.imgtrans = rendering.Transform()
self.img.add_attr(self.imgtrans)
self.viewer.add_onetime(self.img)
self.pole_transform.set_rotation(self.state[0] + np.pi/2)
if self.last_u:
self.imgtrans.scale = (-self.last_u/2, np.abs(self.last_u)/2)
return self.viewer.render(return_rgb_array = mode=='rgb_array')
def close(self):
if self.viewer:
self.viewer.close()
self.viewer = None
def angle_normalize(x):
return (((x+np.pi) % (2*np.pi)) - np.pi)