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 Shape

(214, 160, 3)

Observation High

255

Observation Low

0

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 Discrete(6) with the table below lists the meaning of each action’s meanings. As Carnival uses a reduced set of actions for v0, v4 and v5 versions of the environment. 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 environment have two possible observation types, the observation space is listed below. See variants section for the type of observation used by each environment id.

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

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

Additionally, obs_type="grayscale" cause the environment return a grayscale version of the rgb array for observations with the observation space being Box(0, 255, (210, 160), np.uint8)

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