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sklearn.model_selection._search.GridSearchCV(estimator=sklearn.pipeline.Pipeline(imputer=sklearn.impute._base.SimpleImputer,classifier=sklearn.tree.tree.DecisionTreeClassifier))

sklearn.model_selection._search.GridSearchCV(estimator=sklearn.pipeline.Pipeline(imputer=sklearn.impute._base.SimpleImputer,classifier=sklearn.tree.tree.DecisionTreeClassifier))

Visibility: public Uploaded 11-11-2019 by Continuous Integration sklearn==0.21.2 numpy>=1.6.1 scipy>=0.9 3 runs
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  • openml-python python scikit-learn sklearn sklearn_0.21.2
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Exhaustive search over specified parameter values for an estimator. Important members are fit, predict. GridSearchCV implements a "fit" and a "score" method. It also implements "predict", "predict_proba", "decision_function", "transform" and "inverse_transform" if they are implemented in the estimator used. The parameters of the estimator used to apply these methods are optimized by cross-validated grid-search over a parameter grid.

Components

estimatorsklearn.pipeline.Pipeline(imputer=sklearn.impute._base.SimpleImputer,classifier=sklearn.tree.tree.DecisionTreeClassifier)(9)This is assumed to implement the scikit-learn estimator interface Either estimator needs to provide a ``score`` function, or ``scoring`` must be passed

Parameters

cvDetermines the cross-validation splitting strategy Possible inputs for cv are: - None, to use the default 3-fold cross validation, - integer, to specify the number of folds in a `(Stratified)KFold`, - :term:`CV splitter`, - An iterable yielding (train, test) splits as arrays of indices For integer/None inputs, if the estimator is a classifier and ``y`` is either binary or multiclass, :class:`StratifiedKFold` is used. In all other cases, :class:`KFold` is used Refer :ref:`User Guide ` for the various cross-validation strategies that can be used here .. versionchanged:: 0.20 ``cv`` default value if None will change from 3-fold to 5-fold in v0.22default: "warn"
error_scoreValue to assign to the score if an error occurs in estimator fitting If set to 'raise', the error is raised. If a numeric value is given, FitFailedWarning is raised. This parameter does not affect the refit step, which will always raise the error. Default is 'raise' but from version 0.22 it will change to np.nandefault: "raise-deprecating"
estimatorThis is assumed to implement the scikit-learn estimator interface Either estimator needs to provide a ``score`` function, or ``scoring`` must be passeddefault: {"oml-python:serialized_object": "component_reference", "value": {"key": "estimator", "step_name": null}}
iidIf True, return the average score across folds, weighted by the number of samples in each test set. In this case, the data is assumed to be identically distributed across the folds, and the loss minimized is the total loss per sample, and not the mean loss across the folds. If False, return the average score across folds. Default is True, but will change to False in version 0.22, to correspond to the standard definition of cross-validation .. versionchanged:: 0.20 Parameter ``iid`` will change from True to False by default in version 0.22, and will be removed in 0.24default: "warn"
n_jobsNumber of jobs to run in parallel ``None`` means 1 unless in a :obj:`joblib.parallel_backend` context ``-1`` means using all processors. See :term:`Glossary ` for more detailsdefault: null
param_gridDictionary with parameters names (string) as keys and lists of parameter settings to try as values, or a list of such dictionaries, in which case the grids spanned by each dictionary in the list are explored. This enables searching over any sequence of parameter settingsdefault: {"classifier__max_depth": [1, 2, 3, 4, 5], "imputer__strategy": ["mean", "median"]}
pre_dispatchControls the number of jobs that get dispatched during parallel execution. Reducing this number can be useful to avoid an explosion of memory consumption when more jobs get dispatched than CPUs can process. This parameter can be: - None, in which case all the jobs are immediately created and spawned. Use this for lightweight and fast-running jobs, to avoid delays due to on-demand spawning of the jobs - An int, giving the exact number of total jobs that are spawned - A string, giving an expression as a function of n_jobs, as in '2*n_jobs'default: "2*n_jobs"
refitRefit an estimator using the best found parameters on the whole dataset For multiple metric evaluation, this needs to be a string denoting the scorer that would be used to find the best parameters for refitting the estimator at the end Where there are considerations other than maximum score in choosing a best estimator, ``refit`` can be set to a function which returns the selected ``best_index_`` given ``cv_results_`` The refitted estimator is made available at the ``best_estimator_`` attribute and permits using ``predict`` directly on this ``GridSearchCV`` instance Also for multiple metric evaluation, the attributes ``best_index_``, ``best_score_`` and ``best_params_`` will only be available if ``refit`` is set and all of them will be determined w.r.t this specific scorer. ``best_score_`` is not returned if refit is callable See ``scoring`` parameter to know more about multiple metric evaluation .. versionchanged:: 0.20 Supp...default: true
return_train_scoreIf ``False``, the ``cv_results_`` attribute will not include training scores Computing training scores is used to get insights on how different parameter settings impact the overfitting/underfitting trade-off However computing the scores on the training set can be computationally expensive and is not strictly required to select the parameters that yield the best generalization performance Examples -------- >>> from sklearn import svm, datasets >>> from sklearn.model_selection import GridSearchCV >>> iris = datasets.load_iris() >>> parameters = {'kernel':('linear', 'rbf'), 'C':[1, 10]} >>> svc = svm.SVC(gamma="scale") >>> clf = GridSearchCV(svc, parameters, cv=5) >>> clf.fit(iris.data, iris.target) ... # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS GridSearchCV(cv=5, error_score=..., estimator=SVC(C=1.0, cache_size=..., class_weight=..., coef0=..., decision_function_shape='ovr', degree=..., gamma=..., kernel='...default: false
scoringA single string (see :ref:`scoring_parameter`) or a callable (see :ref:`scoring`) to evaluate the predictions on the test set For evaluating multiple metrics, either give a list of (unique) strings or a dict with names as keys and callables as values NOTE that when using custom scorers, each scorer should return a single value. Metric functions returning a list/array of values can be wrapped into multiple scorers that return one value each See :ref:`multimetric_grid_search` for an example If None, the estimator's score method is useddefault: null
verboseControls the verbosity: the higher, the more messagesdefault: 0

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