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use crate::{ spaces::{real::Interval, ProductSpace, Surjection}, Domain, Observation, Reward, }; const X_MIN: f64 = -1.2; const X_MAX: f64 = 0.6; const V_MIN: f64 = -0.07; const V_MAX: f64 = 0.07; const FORCE_G: f64 = -0.0025; const FORCE_CAR: f64 = 0.0015; const HILL_FREQ: f64 = 3.0; const REWARD_STEP: f64 = -1.0; const REWARD_GOAL: f64 = 0.0; const MIN_ACTION: f64 = -1.0; const MAX_ACTION: f64 = 1.0; pub struct ContinuousMountainCar { x: f64, v: f64, action_space: Interval, } impl ContinuousMountainCar { pub fn new(x: f64, v: f64) -> ContinuousMountainCar { ContinuousMountainCar { x, v, action_space: Interval::bounded(MIN_ACTION, MAX_ACTION), } } fn dv(x: f64, a: f64) -> f64 { FORCE_CAR * a + FORCE_G * (HILL_FREQ * x).cos() } fn update_state(&mut self, a: f64) { let a = self.action_space.map_onto(a); self.v = clip!(V_MIN, self.v + Self::dv(self.x, a), V_MAX); self.x = clip!(X_MIN, self.x + self.v, X_MAX); } } impl Default for ContinuousMountainCar { fn default() -> ContinuousMountainCar { ContinuousMountainCar::new(-0.5, 0.0) } } impl Domain for ContinuousMountainCar { type StateSpace = ProductSpace<Interval>; type ActionSpace = Interval; fn emit(&self) -> Observation<Vec<f64>> { if self.x >= X_MAX { Observation::Terminal(vec![self.x, self.v]) } else { Observation::Full(vec![self.x, self.v]) } } fn step(&mut self, action: &f64) -> (Observation<Vec<f64>>, Reward) { self.update_state(*action); let to = self.emit(); let reward = if to.is_terminal() { REWARD_GOAL } else { REWARD_STEP }; (to, reward) } fn state_space(&self) -> Self::StateSpace { ProductSpace::empty() + Interval::bounded(X_MIN, X_MAX) + Interval::bounded(V_MIN, V_MAX) } fn action_space(&self) -> Interval { Interval::bounded(MIN_ACTION, MAX_ACTION) } } #[cfg(test)] mod tests { use super::*; use crate::{Domain, Observation}; #[test] fn test_initial_observation() { let m = ContinuousMountainCar::default(); match m.emit() { Observation::Full(ref state) => { assert_eq!(state[0], -0.5); assert_eq!(state[1], 0.0); }, _ => panic!("Should yield a fully observable state."), } } #[test] fn test_is_terminal() { assert!(!ContinuousMountainCar::default().emit().is_terminal()); assert!(!ContinuousMountainCar::new(-0.5, 0.0).emit().is_terminal()); assert!(ContinuousMountainCar::new(X_MAX, -0.05) .emit() .is_terminal()); assert!(ContinuousMountainCar::new(X_MAX, 0.0).emit().is_terminal()); assert!(ContinuousMountainCar::new(X_MAX, 0.05).emit().is_terminal()); assert!(!ContinuousMountainCar::new(X_MAX - 0.0001 * X_MAX, 0.0) .emit() .is_terminal()); assert!(ContinuousMountainCar::new(X_MAX + 0.0001 * X_MAX, 0.0) .emit() .is_terminal()); } }