Carnival

../../../_images/carnival.gif

This environment is part of the Atari environments. Please read that page first for general information.

Action Space

Discrete(6)

Observation Space

Box(0, 255, (214, 160, 3), uint8)

Import

gymnasium.make("ALE/Carnival-v5")

For more Carnival variants with different observation and action spaces, see the variants section.

Description

This is a “shoot ‘em up” game. Targets move horizontally across the screen and you must shoot them. You are in control of a gun that can be moved horizontally. The supply of ammunition is limited and chickens may steal some bullets from you if you don’t hit them in time.

For a more detailed documentation, see the AtariAge page

Actions

Carnival has the action space of Discrete(6) with the table below listing the meaning of each action’s meanings. To enable all 18 possible actions that can be performed on an Atari 2600, specify full_action_space=True during initialization or by passing full_action_space=True to gymnasium.make.

Value

Meaning

Value

Meaning

Value

Meaning

0

NOOP

1

FIRE

2

RIGHT

3

LEFT

4

RIGHTFIRE

5

LEFTFIRE

Observations

Atari environments have three possible observation types: "rgb", "grayscale" and "ram".

  • obs_type="rgb" -> observation_space=Box(0, 255, (210, 160, 3), np.uint8)

  • obs_type="ram" -> observation_space=Box(0, 255, (128,), np.uint8)

  • obs_type="grayscale" -> Box(0, 255, (210, 160), np.uint8), a grayscale version of the “rgb” type

See variants section for the type of observation used by each environment id by default.

Rewards

You score points by destroying targets. Points (or bullets) may be subtracted if you hit the target when it shows a minus sign. You will score extra points if it shows a plus sign! For a more detailed documentation, see the AtariAge page.

Variants

Carnival has the following variants of the environment id which have the following differences in observation, the number of frame-skips and the repeat action probability.

Env-id

obs_type=

frameskip=

repeat_action_probability=

Carnival-v0

"rgb"

(2, 5)

0.25

Carnival-ram-v0

"ram"

(2, 5)

0.25

Carnival-ramDeterministic-v0

"ram"

4

0.25

Carnival-ramNoFrameskip-v0

"ram"

1

0.25

CarnivalDeterministic-v0

"rgb"

4

0.25

CarnivalNoFrameskip-v0

"rgb"

1

0.25

Carnival-v4

"rgb"

(2, 5)

0.0

Carnival-ram-v4

"ram"

(2, 5)

0.0

Carnival-ramDeterministic-v4

"ram"

4

0.0

Carnival-ramNoFrameskip-v4

"ram"

1

0.0

CarnivalDeterministic-v4

"rgb"

4

0.0

CarnivalNoFrameskip-v4

"rgb"

1

0.0

ALE/Carnival-v5

"rgb"

4

0.25

ALE/Carnival-ram-v5

"ram"

4

0.25

Difficulty and modes

It is possible to specify various flavors of the environment via the keyword arguments difficulty and mode. A flavor is a combination of a game mode and a difficulty setting. The table below lists the possible difficulty and mode values along with the default values.

Available Modes

Default Mode

Available Difficulties

Default Difficulty

[0]

0

[0]

0

Version History

A thorough discussion of the intricate differences between the versions and configurations can be found in the general article on Atari environments.

  • v5: Stickiness was added back and stochastic frameskipping was removed. The environments are now in the “ALE” namespace.

  • v4: Stickiness of actions was removed

  • v0: Initial versions release