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2026-07-13 13:17:40 +08:00

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"""An example script showing how to define and load an `RLModule` that applies
action masking
This example:
- Defines an `RLModule` that applies action masking.
- It does so by using a `gymnasium.spaces.dict.Dict` observation space
with two keys, namely `"observations"`, holding the original observations
and `"action_mask"` defining the action mask for the current environment
state. Note, by this definition you can wrap any `gymnasium` environment
and use it for this module.
- Furthermore, it derives its `TorchRLModule` from the `PPOTorchRLModule` and
can therefore be easily plugged into our `PPO` algorithm.
- It overrides the `forward` methods of the `PPOTorchRLModule` to apply the
action masking and it overrides the `_compute_values` method for GAE
computation to extract the `"observations"` from the batch `Columns.OBS`
key.
- It uses the custom `ActionMaskEnv` that defines for each step a new action
mask that defines actions that are allowed (1.0) and others that are not
(0.0).
- It runs 10 iterations with PPO and finishes.
How to run this script
----------------------
`python [script file name].py --num-env-runners 2`
Control the number of `EnvRunner`s with the `--num-env-runners` flag. This
will increase the sampling speed.
For debugging, use the following additional command line options
`--no-tune --num-env-runners=0`
which should allow you to set breakpoints anywhere in the RLlib code and
have the execution stop there for inspection and debugging.
For logging to your WandB account, use:
`--wandb-key=[your WandB API key] --wandb-project=[some project name]
--wandb-run-name=[optional: WandB run name (within the defined project)]`
Results to expect
-----------------
You should expect a mean episode reward of around 0.35. The environment is a random
environment paying out random rewards - so the agent cannot learn, but it can obey the
action mask and should do so (no `AssertionError` should happen).
After 40,000 environment steps and 10 training iterations the run should stop
successfully:
+-------------------------------+------------+----------------------+--------+
| Trial name | status | loc | iter |
| | | | |
|-------------------------------+------------+----------------------+--------+
| PPO_ActionMaskEnv_dedc8_00000 | TERMINATED | 192.168.1.178:103298 | 10 |
+-------------------------------+------------+----------------------+--------+
+------------------+------------------------+------------------------+
| total time (s) | num_env_steps_sample | num_env_steps_traine |
| | d_lifetime | d_lifetime |
+------------------+------------------------+------------------------+
| 57.9207 | 40000 | 40000 |
+------------------+------------------------+------------------------+
*------------------------+
| num_episodes_lifetim |
| e |
+------------------------|
| 3898 |
+------------------------+
"""
from gymnasium.spaces import Box, Discrete
from ray.rllib.algorithms.ppo import PPOConfig
from ray.rllib.core.rl_module.rl_module import RLModuleSpec
from ray.rllib.examples.envs.classes.action_mask_env import ActionMaskEnv
from ray.rllib.examples.rl_modules.classes.action_masking_rlm import (
ActionMaskingTorchRLModule,
)
from ray.rllib.examples.utils import (
add_rllib_example_script_args,
run_rllib_example_script_experiment,
)
parser = add_rllib_example_script_args(
default_iters=10,
default_timesteps=100000,
default_reward=150.0,
)
if __name__ == "__main__":
args = parser.parse_args()
if args.algo != "PPO":
raise ValueError("This example only supports PPO. Please use --algo=PPO.")
base_config = (
PPOConfig()
.environment(
env=ActionMaskEnv,
env_config={
"action_space": Discrete(100),
# This defines the 'original' observation space that is used in the
# `RLModule`. The environment will wrap this space into a
# `gym.spaces.Dict` together with an 'action_mask' that signals the
# `RLModule` to adapt the action distribution inputs for the underlying
# `DefaultPPORLModule`.
"observation_space": Box(-1.0, 1.0, (5,)),
},
)
.rl_module(
# We need to explicitly specify here RLModule to use and
# the catalog needed to build it.
rl_module_spec=RLModuleSpec(
module_class=ActionMaskingTorchRLModule,
model_config={
"head_fcnet_hiddens": [64, 64],
"head_fcnet_activation": "relu",
},
),
)
.evaluation(
evaluation_num_env_runners=1,
evaluation_interval=1,
# Run evaluation parallel to training to speed up the example.
evaluation_parallel_to_training=True,
)
)
# Run the example (with Tune).
run_rllib_example_script_experiment(base_config, args)