The source code and dockerfile for the GSW2024 AI Lab.
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from __future__ import annotations
from minigrid.core.constants import COLOR_NAMES
from minigrid.core.grid import Grid
from minigrid.core.mission import MissionSpace
from minigrid.core.world_object import Ball, Key
from minigrid.minigrid_env import MiniGridEnv
class FetchEnv(MiniGridEnv):
"""
## Description
This environment has multiple objects of assorted types and colors. The
agent receives a textual string as part of its observation telling it which
object to pick up. Picking up the wrong object terminates the episode with
zero reward.
## Mission Space
"{syntax} {color} {type}"
{syntax} is one of the following: "get a", "go get a", "fetch a",
"go fetch a", "you must fetch a".
{color} is the color of the box. Can be "red", "green", "blue", "purple",
"yellow" or "grey".
{type} is the type of the object. Can be "key" or "ball".
## Action Space
| Num | Name | Action |
|-----|--------------|----------------------|
| 0 | left | Turn left |
| 1 | right | Turn right |
| 2 | forward | Move forward |
| 3 | pickup | Pick up an object |
| 4 | drop | Unused |
| 5 | toggle | Unused |
| 6 | done | Unused |
## Observation Encoding
- Each tile is encoded as a 3 dimensional tuple:
`(OBJECT_IDX, COLOR_IDX, STATE)`
- `OBJECT_TO_IDX` and `COLOR_TO_IDX` mapping can be found in
[minigrid/minigrid.py](minigrid/minigrid.py)
- `STATE` refers to the door state with 0=open, 1=closed and 2=locked
## Rewards
A reward of '1 - 0.9 * (step_count / max_steps)' is given for success, and '0' for failure.
## Termination
The episode ends if any one of the following conditions is met:
1. The agent picks up the correct object.
2. The agent picks up the wrong object.
2. Timeout (see `max_steps`).
## Registered Configurations
N: number of objects to be generated.
- `MiniGrid-Fetch-5x5-N2-v0`
- `MiniGrid-Fetch-6x6-N2-v0`
- `MiniGrid-Fetch-8x8-N3-v0`
"""
def __init__(self, size=8, numObjs=3, max_steps: int | None = None, **kwargs):
self.numObjs = numObjs
self.obj_types = ["key", "ball"]
MISSION_SYNTAX = [
"get a",
"go get a",
"fetch a",
"go fetch a",
"you must fetch a",
]
self.size = size
mission_space = MissionSpace(
mission_func=self._gen_mission,
ordered_placeholders=[MISSION_SYNTAX, COLOR_NAMES, self.obj_types],
)
if max_steps is None:
max_steps = 5 * size**2
super().__init__(
mission_space=mission_space,
width=size,
height=size,
# Set this to True for maximum speed
see_through_walls=True,
max_steps=max_steps,
**kwargs,
)
@staticmethod
def _gen_mission(syntax: str, color: str, obj_type: str):
return f"{syntax} {color} {obj_type}"
def _gen_grid(self, width, height):
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)
objs = []
# For each object to be generated
while len(objs) < self.numObjs:
objType = self._rand_elem(self.obj_types)
objColor = self._rand_elem(COLOR_NAMES)
if objType == "key":
obj = Key(objColor)
elif objType == "ball":
obj = Ball(objColor)
else:
raise ValueError(
"{} object type given. Object type can only be of values key and ball.".format(
objType
)
)
self.place_obj(obj)
objs.append(obj)
# Randomize the player start position and orientation
self.place_agent()
# Choose a random object to be picked up
target = objs[self._rand_int(0, len(objs))]
self.targetType = target.type
self.targetColor = target.color
descStr = f"{self.targetColor} {self.targetType}"
# Generate the mission string
idx = self._rand_int(0, 5)
if idx == 0:
self.mission = "get a %s" % descStr
elif idx == 1:
self.mission = "go get a %s" % descStr
elif idx == 2:
self.mission = "fetch a %s" % descStr
elif idx == 3:
self.mission = "go fetch a %s" % descStr
elif idx == 4:
self.mission = "you must fetch a %s" % descStr
assert hasattr(self, "mission")
def step(self, action):
obs, reward, terminated, truncated, info = super().step(action)
if self.carrying:
if (
self.carrying.color == self.targetColor
and self.carrying.type == self.targetType
):
reward = self._reward()
terminated = True
else:
reward = 0
terminated = True
return obs, reward, terminated, truncated, info