Gym-MiniGrid/gym_minigrid/envs/playground.py

from gym_minigrid.minigrid import (
    COLOR_NAMES,
    Ball,
    Box,
    Door,
    Grid,
    Key,
    MiniGridEnv,
    MissionSpace,
)


class PlaygroundEnv(MiniGridEnv):
    """
    Environment with multiple rooms and random objects.
    This environment has no specific goals or rewards.
    """

    def __init__(self, **kwargs):
        mission_space = MissionSpace(mission_func=lambda: "")
        self.size = 19
        super().__init__(
            mission_space=mission_space,
            width=self.size,
            height=self.size,
            max_steps=100,
            **kwargs
        )

    def _gen_grid(self, width, height):
        # Create the grid
        self.grid = Grid(width, height)

        # Generate the surrounding walls
        self.grid.horz_wall(0, 0)
        self.grid.horz_wall(0, height - 1)
        self.grid.vert_wall(0, 0)
        self.grid.vert_wall(width - 1, 0)

        roomW = width // 3
        roomH = height // 3

        # For each row of rooms
        for j in range(0, 3):

            # For each column
            for i in range(0, 3):
                xL = i * roomW
                yT = j * roomH
                xR = xL + roomW
                yB = yT + roomH

                # Bottom wall and door
                if i + 1 < 3:
                    self.grid.vert_wall(xR, yT, roomH)
                    pos = (xR, self._rand_int(yT + 1, yB - 1))
                    color = self._rand_elem(COLOR_NAMES)
                    self.grid.set(*pos, Door(color))

                # Bottom wall and door
                if j + 1 < 3:
                    self.grid.horz_wall(xL, yB, roomW)
                    pos = (self._rand_int(xL + 1, xR - 1), yB)
                    color = self._rand_elem(COLOR_NAMES)
                    self.grid.set(*pos, Door(color))

        # Randomize the player start position and orientation
        self.place_agent()

        # Place random objects in the world
        types = ["key", "ball", "box"]
        for i in range(0, 12):
            objType = self._rand_elem(types)
            objColor = self._rand_elem(COLOR_NAMES)
            if objType == "key":
                obj = Key(objColor)
            elif objType == "ball":
                obj = Ball(objColor)
            elif objType == "box":
                obj = Box(objColor)
            else:
                raise ValueError(
                    "{} object type given. Object type can only be of values key, ball and box.".format(
                        objType
                    )
                )
            self.place_obj(obj)

        # No explicit mission in this environment
        self.mission = ""