Path_Planning_Algo_with_Animations/Stochastic Shortest Path/env.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
@author: huiming zhou
"""

x_range, y_range = 51, 31     # size of background


def obs_map():
    """
    Initialize obstacles' positions

    :return: map of obstacles
    """

    obs = []
    for i in range(x_range):
        obs.append((i, 0))
    for i in range(x_range):
        obs.append((i, y_range - 1))

    for i in range(y_range):
        obs.append((0, i))
    for i in range(y_range):
        obs.append((x_range - 1, i))

    for i in range(10, 21):
        obs.append((i, 15))
    for i in range(15):
        obs.append((20, i))

    for i in range(15, 30):
        obs.append((30, i))
    for i in range(16):
        obs.append((40, i))

    return obs


def lose_map():
    """
    Initialize losing states' positions
    :return: losing states
    """

    lose = []
    for i in range(25, 36):
        lose.append((i, 13))
        
    return lose


def get_reward(x_next, xG, lose):
    """
    calculate reward of next state

    :param x_next: next state
    :return: reward
    """

    reward = []
    for x in x_next:
        if x in xG:
            reward.append(10)           # reward : 10, for goal states
        elif x in lose:
            reward.append(-10)          # reward : -10, for lose states
        else:
            reward.append(0)            # reward : 0, for other states

    return reward