"""
.. _attributes:

User Attributes
===============

This feature is to annotate experiments with user-defined attributes.
"""

###################################################################################################
# Adding User Attributes to Studies
# ---------------------------------
#
# A :class:`~optuna.study.Study` object provides :func:`~optuna.study.Study.set_user_attr` method
# to register a pair of key and value as an user-defined attribute.
# A key is supposed to be a ``str``, and a value be any object serializable with ``json.dumps``.

import sklearn.datasets
import sklearn.svm
import sklearn.model_selection
import optuna
study = optuna.create_study(storage='sqlite:///example.db')
study.set_user_attr('contributors', ['Akiba', 'Sano'])
study.set_user_attr('dataset', 'MNIST')


###################################################################################################
# We can access annotated attributes with :attr:`~optuna.study.Study.user_attr` property.


study.user_attrs  # {'contributors': ['Akiba', 'Sano'], 'dataset': 'MNIST'}

###################################################################################################
# :class:`~optuna.struct.StudySummary` object, which can be retrieved by
# :func:`~optuna.study.get_all_study_summaries`, also contains user-defined attributes.


study_summaries = optuna.get_all_study_summaries('sqlite:///example.db')
study_summaries[0].user_attrs  # {'contributors': ['Akiba', 'Sano'], 'dataset': 'MNIST'}


###################################################################################################
# .. seealso::
#     ``optuna study set-user-attr`` command, which sets an attribute via command line interface.


###################################################################################################
# Adding User Attributes to Trials
# --------------------------------
#
# As with :class:`~optuna.study.Study`, a :class:`~optuna.trial.Trial` object provides
# :func:`~optuna.trial.Trial.set_user_attr` method.
# Attributes are set inside an objective function.


def objective(trial):
    iris = sklearn.datasets.load_iris()
    x, y = iris.data, iris.target

    svc_c = trial.suggest_loguniform('svc_c', 1e-10, 1e10)
    clf = sklearn.svm.SVC(C=svc_c)
    accuracy = sklearn.model_selection.cross_val_score(clf, x, y).mean()

    trial.set_user_attr('accuracy', accuracy)

    return 1.0 - accuracy  # return error for minimization


study.optimize(objective, n_trials=1)

###################################################################################################
# We can access annotated attributes as:

study.trials[0].user_attrs

###################################################################################################
# Note that, in this example, the attribute is not annotated to a :class:`~optuna.study.Study`
# but a single :class:`~optuna.trial.Trial`.