Command-Line Interface

Command	Description
ask	Create a new trial and suggest parameters.
best-trial	Show the best trial.
best-trials	Show a list of trials located at the Pareto front.
create-study	Create a new study.
delete-study	Delete a specified study.
storage upgrade	Upgrade the schema of a storage.
studies	Show a list of studies.
study set-user-attr	Set a user attribute to a study.
tell	Finish a trial, which was created by the ask command.
trials	Show a list of trials.

Optuna provides command-line interface as shown in the above table.

Let us assume you are not in IPython shell and writing Python script files instead. It is totally fine to write scripts like the following:

import optuna


def objective(trial):
    x = trial.suggest_float("x", -10, 10)
    return (x - 2) ** 2


if __name__ == "__main__":
    study = optuna.create_study()
    study.optimize(objective, n_trials=100)
    print("Best value: {} (params: {})\n".format(study.best_value, study.best_params))

Best value: 3.5523660363699647e-07 (params: {'x': 2.0005960172846797})

However, if we cannot write objective explicitly in Python code such as developing a new drug in a lab, an interactive way is suitable. In Optuna CLI, Ask-and-Tell Interface style commands provide such an interactive and flexible interface.

Let us assume we minimize the objective value depending on a parameter x in \([-10, 10]\) and objective value is calculated via some experiments by hand. Even so, we can invoke the optimization as follows. Don’t care about --storage sqlite:///example.db for now, which is described in Saving/Resuming Study with RDB Backend.

$ STUDY_NAME=`optuna create-study --storage sqlite:///example.db`
$ optuna ask --storage sqlite:///example.db --study-name $STUDY_NAME --sampler TPESampler \
     --search-space '{"x": {"name": "FloatDistribution", "attributes": {"step": null, "low": -10.0, "high": 10.0, "log": false}}}'


[I 2022-08-20 06:08:53,158] Asked trial 0 with parameters {'x': 2.512238141966016}.
{"number": 0, "params": {"x": 2.512238141966016}}

The argument of --search-space option can be generated by using optuna.distributions.distribution_to_json(), for example, optuna.distributions.distribution_to_json(optuna.distributions.FloatDistribution(-10, 10)). Please refer to optuna.distributions.FloatDistribution and optuna.distributions.IntDistribution for detailed explanations of their arguments.

After conducting an experiment using the suggested parameter in the lab, we store the result to Optuna’s study as follows:

$ optuna tell --storage sqlite:///example.db --study-name $STUDY_NAME --trial-number 0 --values 0.7 --state complete
[I 2022-08-20 06:22:50,888] Told trial 0 with values [0.7] and state TrialState.COMPLETE.