optuna のエラー

study = optuna.create_study()
と入力すると下記の様なエラーが発生します。
これはどういった意味なのでしょうか。

[I 2021-07-03 22:10:30,989] A new study created in memory with name: no-name-a8b1c2a9-c9b5-4066-b118-5828d8d64418

行動規範の内容に同意します

回答1件

エラーではありません。

名前付き引数storageと名前付き引数study_nameが指定されなかったため、memory上に"no-name-a8b1c2a9-c9b5-4066-b118-5828d8d64418"という名前でクラスoptuna.study.Studyのインスタンスを作成しました、という情報を伝えているだけです。

こういうものがわからない場合は、以下の方法でDoc stringを確認しましょう。

python
1>>> print(optuna.create_study.__doc__)
2Create a new :class:`~optuna.study.Study`.
3
4    Example:
5
6        .. testcode::
7
8            import optuna
9
10
11            def objective(trial):
12                x = trial.suggest_float("x", 0, 10)
13                return x ** 2
14
15
16            study = optuna.create_study()
17            study.optimize(objective, n_trials=3)
18
19    Args:
20        storage:
21            Database URL. If this argument is set to None, in-memory storage is used, and the
22            :class:`~optuna.study.Study` will not be persistent.
23
24            .. note::
25                When a database URL is passed, Optuna internally uses `SQLAlchemy`_ to handle
26                the database. Please refer to `SQLAlchemy's document`_ for further details.
27                If you want to specify non-default options to `SQLAlchemy Engine`_, you can
28                instantiate :class:`~optuna.storages.RDBStorage` with your desired options and
29                pass it to the ``storage`` argument instead of a URL.
30
31             .. _SQLAlchemy: https://www.sqlalchemy.org/
32             .. _SQLAlchemy's document:
33                 https://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls
34             .. _SQLAlchemy Engine: https://docs.sqlalchemy.org/en/latest/core/engines.html
35
36        sampler:
37            A sampler object that implements background algorithm for value suggestion.
38            If :obj:`None` is specified, :class:`~optuna.samplers.TPESampler` is used during
39            single-objective optimization and :class:`~optuna.samplers.NSGAIISampler` during
40            multi-objective optimization. See also :class:`~optuna.samplers`.
41        pruner:
42            A pruner object that decides early stopping of unpromising trials. If :obj:`None`
43            is specified, :class:`~optuna.pruners.MedianPruner` is used as the default. See
44            also :class:`~optuna.pruners`.
45        study_name:
46            Study's name. If this argument is set to None, a unique name is generated
47            automatically.
48        direction:
49            Direction of optimization. Set ``minimize`` for minimization and ``maximize`` for
50            maximization. You can also pass the corresponding :class:`~optuna.study.StudyDirection`
51            object.
52
53            .. note::
54                If none of `direction` and `directions` are specified, the direction of the study
55                is set to "minimize".
56        load_if_exists:
57            Flag to control the behavior to handle a conflict of study names.
58            In the case where a study named ``study_name`` already exists in the ``storage``,
59            a :class:`~optuna.exceptions.DuplicatedStudyError` is raised if ``load_if_exists`` is
60            set to :obj:`False`.
61            Otherwise, the creation of the study is skipped, and the existing one is returned.
62        directions:
63            A sequence of directions during multi-objective optimization.
64
65    Returns:
66        A :class:`~optuna.study.Study` object.
67
68    Raises:
69        :exc:`ValueError`:
70            If the length of ``directions`` is zero.
71            Or, if ``direction`` is neither 'minimize' nor 'maximize' when it is a string.
72            Or, if the element of ``directions`` is neither `minimize` nor `maximize`.
73            Or, if both ``direction`` and ``directions`` are specified.
74
75    See also:
76        :func:`optuna.create_study` is an alias of :func:`optuna.study.create_study`.