Galaxian#
This environment is part of the Atari environments. Please read that page first for general information.
Action Space |
Discrete(6) |
Observation Shape |
(210, 160, 3) |
Observation High |
255 |
Observation Low |
0 |
Import |
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For more Galaxian variants with different observation and action spaces, see the variants section.
Description#
Galaxian is missing description documentation. If you are interested in writing up a description, please create an issue or PR with the information on the Gymnasium github.
Actions#
Galaxian has the action space Discrete(6) with the table below lists the meaning of each action’s meanings.
As Galaxian 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 |
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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)
Variants#
Galaxian 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= |
|---|---|---|---|
ALE/Galaxian-v5 |
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ALE/Galaxian-ram-v5 |
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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 |
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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