def heuristic()

in gym/envs/box2d/lunar_lander.py [0:0]

• 28 lines of code
• 10 McCabe index (conditional complexity)

def heuristic(env, s):
    """
    The heuristic for
    1. Testing
    2. Demonstration rollout.

    Args:
        env: The environment
        s (list): The state. Attributes:
            s[0] is the horizontal coordinate
            s[1] is the vertical coordinate
            s[2] is the horizontal speed
            s[3] is the vertical speed
            s[4] is the angle
            s[5] is the angular speed
            s[6] 1 if first leg has contact, else 0
            s[7] 1 if second leg has contact, else 0

    Returns:
         a: The heuristic to be fed into the step function defined above to determine the next step and reward.
    """

    angle_targ = s[0] * 0.5 + s[2] * 1.0  # angle should point towards center
    if angle_targ > 0.4:
        angle_targ = 0.4  # more than 0.4 radians (22 degrees) is bad
    if angle_targ < -0.4:
        angle_targ = -0.4
    hover_targ = 0.55 * np.abs(
        s[0]
    )  # target y should be proportional to horizontal offset

    angle_todo = (angle_targ - s[4]) * 0.5 - (s[5]) * 1.0
    hover_todo = (hover_targ - s[1]) * 0.5 - (s[3]) * 0.5

    if s[6] or s[7]:  # legs have contact
        angle_todo = 0
        hover_todo = (
            -(s[3]) * 0.5
        )  # override to reduce fall speed, that's all we need after contact

    if env.continuous:
        a = np.array([hover_todo * 20 - 1, -angle_todo * 20])
        a = np.clip(a, -1, +1)
    else:
        a = 0
        if hover_todo > np.abs(angle_todo) and hover_todo > 0.05:
            a = 2
        elif angle_todo < -0.05:
            a = 3
        elif angle_todo > +0.05:
            a = 1
    return a