Uno
This environment is part of the classic environments. Please read that page first for general information.
| Name | Value |
|---|---|
| Actions | Discrete |
| Agents | 2 |
| Parallel API | Yes |
| Manual Control | No |
| Action Shape | Discrete(61) |
| Action Values | Discrete(61) |
| Observation Shape | (7, 4, 15) |
| Observation Values | [0, 1] |
| Import | from pettingzoo.classic import uno_v1 |
| Agents | agents= ['player_0', 'player_1'] |
Agent Environment Cycle
Uno
Uno is shedding game involving 2 players. At the beginning, each player receives 7 cards and the winner is the first player with no cards left. In order to discard a card from their hand, a player must match either the color or number of the card on top of the discard pile. If the player does not have a card to discard, then they will take a card from the draw pile. The deck of cards include 4 colors (blue, green, yellow, and red), 10 numbers (0 to 9), and special cards (Wild, Wild Draw Four, Draw Two, Skip, and Reverse).
Our implementation wraps RLCard and you can refer to its documentation for additional details. Please cite their work if you use this game in research.
Environment parameters
uno.env(opponents_hand_visible=False)
opponents_hand_visible: Set to True to observe the entire observation space as described in Observation Space below. Setting it to False will remove any observation of the opponent’ hands and the observation space will only include planes 0 to 3.
Observation Space
The observation is a dictionary which contains an 'obs' element which is the usual RL observation described below, and an 'action_mask' which holds the legal moves, described in the Legal Actions Mask section.
The main observation space has a shape of (7, 4, 15). Planes 0-2 represent the current player’s hand, while planes 4-6 represent the opponent’s hand. For these sets of planes, the first index indicates the number of copies of a card, the second index the color, and the last index the card number (including any special cards). Uno is played with 2 identical decks, so a player can have 0, 1, or 2 copies of a given card, which is why each player has 3 planes to represent their hand.
| Plane | Feature |
|---|---|
| 0 | Cards that the current player has 0 copies of in their hand |
| 1 | Cards that the current player has 1 copy of in their hand |
| 2 | Cards that the current player has 2 copies of in their hand |
| 3 | Target card (top of the Discard pile) |
| 4 | Cards that the opponent has 0 copies of in their hand |
| 5 | Cards that the opponent has 1 copy of in their hand |
| 6 | Cards that the opponent has 2 copies of in their hand |
Encoding per Plane
| Plane Row Index | Description |
|---|---|
| 0 | Red |
| 1 | Green |
| 2 | Blue |
| 3 | Yellow |
| Plane Column Index | Description |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| … | … |
| 9 | 9 |
| 10 | Wild |
| 11 | Wild Draw Four |
| 12 | Skip |
| 13 | Draw Two |
| 14 | Reverse |
Legal Actions Mask
The legal moves available to the current agent are found in the action_mask element of the dictionary observation. The action_mask is a binary vector where each index of the vector represents whether the action is legal or not. The action_mask will be all zeros for any agent except the one whos turn it is. Taking an illegal move ends the game with a reward of -1 for the illegally moving agent and a reward of 0 for all other agents.
Action Space
The action space is as described by RLCards.
| Action ID | Action |
|---|---|
| 0 - 9 | Red number cards0: 0-Red, 1: 1-Red, …, 9: 9-Red |
| 10 - 12 | Red action cards10: Skip, 11: Reverse, 12: Draw 2 |
| 13 | Red “Wild” card |
| 14 | Red “Wild and Draw 4” card |
| 15 - 24 | Green number cards15: 0-Green, 16: 1-Green, …, 24: 9-Green |
| 25 - 27 | Green action cards25: Skip, 26: Reverse, 27: Draw 2 |
| 28 | Green “Wild” card |
| 29 | Green “Wild and draw 4” card |
| 30 - 39 | Blue number cards30: 0-Blue, 31: 1-Blue, …, 39: 9-Blue |
| 40 - 42 | Blue action cards40: Skip, 41: Reverse, 42: Draw 2 |
| 43 | Blue “Wild” card |
| 44 | Blue “Wild and Draw 4” card |
| 45 - 54 | Yellow number cards45: 0-Yellow, 46: 1-Yellow, …, 54: 9-Yellow |
| 55 - 57 | Yellow action cards55: Skip, 56: Reverse, 57: Draw 2 |
| 58 | Yellow “Wild” card |
| 59 | Yellow “Wild and Draw 4” card |
| 60 | Draw |
For example, you would use action 6 to put down a red “6” card or action 60 to draw a card.
Rewards
| Winner | Loser |
|---|---|
| +1 | -1 |