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ray-project--ray/python/ray/tune/examples/optuna_define_by_run_example.py
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2026-07-13 13:17:40 +08:00

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Python

"""This example demonstrates the usage of Optuna define-by-run with Ray Tune.
It also checks that it is usable with a separate scheduler.
Requires the Optuna library to be installed (`pip install optuna`).
For an example of using a Tune search space, see
:doc:`/tune/examples/optuna_example`.
"""
import time
from typing import Any, Dict, Optional
import ray
from ray import tune
from ray.tune.schedulers import AsyncHyperBandScheduler
from ray.tune.search import ConcurrencyLimiter
from ray.tune.search.optuna import OptunaSearch
def evaluation_fn(step, width, height, mult=1):
return (0.1 + width * step / 100) ** (-1) + height * 0.1 * mult
def easy_objective(config):
# Hyperparameters
width, height, mult = config["width"], config["height"], config.get("mult", 1)
print(config)
for step in range(config["steps"]):
# Iterative training function - can be any arbitrary training procedure
intermediate_score = evaluation_fn(step, width, height, mult)
# Feed the score back back to Tune.
tune.report({"iterations": step, "mean_loss": intermediate_score})
time.sleep(0.1)
def define_by_run_func(trial) -> Optional[Dict[str, Any]]:
"""Define-by-run function to create the search space.
Ensure no actual computation takes place here. That should go into
the trainable passed to ``Tuner`` (in this example, that's
``easy_objective``).
For more information, see https://optuna.readthedocs.io/en/stable\
/tutorial/10_key_features/002_configurations.html
This function should either return None or a dict with constant values.
"""
# This param is not used in the objective function.
activation = trial.suggest_categorical("activation", ["relu", "tanh"])
trial.suggest_float("width", 0, 20)
trial.suggest_float("height", -100, 100)
# Define-by-run allows for conditional search spaces.
if activation == "relu":
trial.suggest_float("mult", 1, 2)
# Return all constants in a dictionary.
return {"steps": 100}
def run_optuna_tune(smoke_test=False):
algo = OptunaSearch(space=define_by_run_func, metric="mean_loss", mode="min")
algo = ConcurrencyLimiter(algo, max_concurrent=4)
scheduler = AsyncHyperBandScheduler()
tuner = tune.Tuner(
easy_objective,
tune_config=tune.TuneConfig(
metric="mean_loss",
mode="min",
search_alg=algo,
scheduler=scheduler,
num_samples=10 if smoke_test else 100,
),
)
results = tuner.fit()
print("Best hyperparameters found were: ", results.get_best_result().config)
if __name__ == "__main__":
import argparse
parser = argparse.ArgumentParser()
parser.add_argument(
"--smoke-test", action="store_true", help="Finish quickly for testing"
)
args, _ = parser.parse_known_args()
ray.init(configure_logging=False)
run_optuna_tune(smoke_test=args.smoke_test)