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114 lines
3.4 KiB
114 lines
3.4 KiB
from __future__ import annotations
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from minigrid.core.grid import Grid
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from minigrid.core.mission import MissionSpace
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from minigrid.core.world_object import Goal
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from minigrid.minigrid_env import MiniGridEnv
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class EmptyEnv(MiniGridEnv):
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"""
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## Description
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This environment is an empty room, and the goal of the agent is to reach the
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green goal square, which provides a sparse reward. A small penalty is
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subtracted for the number of steps to reach the goal. This environment is
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useful, with small rooms, to validate that your RL algorithm works
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correctly, and with large rooms to experiment with sparse rewards and
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exploration. The random variants of the environment have the agent starting
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at a random position for each episode, while the regular variants have the
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agent always starting in the corner opposite to the goal.
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## Mission Space
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"get to the green goal square"
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## Action Space
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| Num | Name | Action |
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|-----|--------------|--------------|
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| 0 | left | Turn left |
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| 1 | right | Turn right |
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| 2 | forward | Move forward |
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| 3 | pickup | Unused |
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| 4 | drop | Unused |
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| 5 | toggle | Unused |
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| 6 | done | Unused |
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## Observation Encoding
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- Each tile is encoded as a 3 dimensional tuple:
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`(OBJECT_IDX, COLOR_IDX, STATE)`
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- `OBJECT_TO_IDX` and `COLOR_TO_IDX` mapping can be found in
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[minigrid/minigrid.py](minigrid/minigrid.py)
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- `STATE` refers to the door state with 0=open, 1=closed and 2=locked
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## Rewards
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A reward of '1 - 0.9 * (step_count / max_steps)' is given for success, and '0' for failure.
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## Termination
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The episode ends if any one of the following conditions is met:
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1. The agent reaches the goal.
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2. Timeout (see `max_steps`).
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## Registered Configurations
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- `MiniGrid-Empty-5x5-v0`
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- `MiniGrid-Empty-Random-5x5-v0`
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- `MiniGrid-Empty-6x6-v0`
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- `MiniGrid-Empty-Random-6x6-v0`
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- `MiniGrid-Empty-8x8-v0`
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- `MiniGrid-Empty-16x16-v0`
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"""
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def __init__(
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self,
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size=8,
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agent_start_pos=(1, 1),
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agent_start_dir=0,
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max_steps: int | None = None,
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**kwargs,
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):
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self.agent_start_pos = agent_start_pos
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self.agent_start_dir = agent_start_dir
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mission_space = MissionSpace(mission_func=self._gen_mission)
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if max_steps is None:
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max_steps = 4 * size**2
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super().__init__(
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mission_space=mission_space,
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grid_size=size,
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# Set this to True for maximum speed
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see_through_walls=True,
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max_steps=max_steps,
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**kwargs,
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)
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@staticmethod
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def _gen_mission():
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return "get to the green goal square"
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def _gen_grid(self, width, height):
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# Create an empty grid
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self.grid = Grid(width, height)
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# Generate the surrounding walls
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self.grid.wall_rect(0, 0, width, height)
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# Place a goal square in the bottom-right corner
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self.put_obj(Goal(), width - 2, height - 2)
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# Place the agent
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if self.agent_start_pos is not None:
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self.agent_pos = self.agent_start_pos
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self.agent_dir = self.agent_start_dir
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else:
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self.place_agent()
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self.mission = "get to the green goal square"
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