Gym-MiniGrid/docs/environments/fetch.md

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title: Fetch

Fetch

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
• STATE refers to the door state with 0=open, 1=closed and 2=locked

Rewards

A reward of '1' 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.
3. 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