(Error-Correcting) Output-Code multiclass strategy
Output-code based strategies consist in representing each class with a binary code (an array of 0s and 1s). At fitting time, one binary classifier per bit in the code book is fitted. At prediction time, the classifiers are used to project new points in the class space and the class closest to the points is chosen. The main advantage of these strategies is that the number of classifiers used can be controlled by the user, either for compressing the model (0 < code_size < 1) or for making the model more robust to errors (code_size > 1). See the documentation for more details.
Read more in the :ref:`User Guide <ecoc>`.
Parameters ---------- estimator : estimator object An estimator object implementing :term:`fit` and one of :term:`decision_function` or :term:`predict_proba`.
code_size : float Percentage of the number of classes to be used to create the code book. A number between 0 and 1 will require fewer classifiers than one-vs-the-rest. A number greater than 1 will require more classifiers than one-vs-the-rest.
random_state : int, RandomState instance or None, optional, default: None The generator used to initialize the codebook. If int, random_state is the seed used by the random number generator; If RandomState instance, random_state is the random number generator; If None, the random number generator is the RandomState instance used by `np.random`.
n_jobs : int or None, optional (default=None) The number of jobs to use for the computation. ``None`` means 1 unless in a :obj:`joblib.parallel_backend` context. ``-1`` means using all processors. See :term:`Glossary <n_jobs>` for more details.
Attributes ---------- estimators_ : list of `int(n_classes * code_size)` estimators Estimators used for predictions.
classes_ : numpy array of shape n_classes
Array containing labels.
code_book_ : numpy array of shape n_classes, code_size
Binary array containing the code of each class.
Examples -------- >>> from sklearn.multiclass import OutputCodeClassifier >>> from sklearn.ensemble import RandomForestClassifier >>> from sklearn.datasets import make_classification >>> X, y = make_classification(n_samples=100, n_features=4, ... n_informative=2, n_redundant=0, ... random_state=0, shuffle=False) >>> clf = OutputCodeClassifier( ... estimator=RandomForestClassifier(random_state=0), ... random_state=0).fit(X, y) >>> clf.predict([0, 0, 0, 0]
) array(1
)
References ----------
.. 1
"Solving multiclass learning problems via error-correcting output codes", Dietterich T., Bakiri G., Journal of Artificial Intelligence Research 2, 1995.
.. 2
"The error coding method and PICTs", James G., Hastie T., Journal of Computational and Graphical statistics 7, 1998.
.. 3
"The Elements of Statistical Learning", Hastie T., Tibshirani R., Friedman J., page 606 (second-edition) 2008.