Mixin class for all regression estimators in scikit-learn.
This mixin defines the following functionality:
set estimator type to "regressor"
through the estimator_type
tag;
score
method that default to r2_score
.
enforce that fit
requires y
to be passed through the requires_y
tag, which is done by setting the regressor type tag.
Read more in the User Guide.
Examples
>>> import numpy as np >>> from sklearn.base import BaseEstimator, RegressorMixin >>> # Mixin classes should always be on the left-hand side for a correct MRO >>> class MyEstimator(RegressorMixin, BaseEstimator): ... def __init__(self, *, param=1): ... self.param = param ... def fit(self, X, y=None): ... self.is_fitted_ = True ... return self ... def predict(self, X): ... return np.full(shape=X.shape[0], fill_value=self.param) >>> estimator = MyEstimator(param=0) >>> X = np.array([[1, 2], [2, 3], [3, 4]]) >>> y = np.array([-1, 0, 1]) >>> estimator.fit(X, y).predict(X) array([0, 0, 0]) >>> estimator.score(X, y) 0.0
Return coefficient of determination on test data.
The coefficient of determination, \(R^2\), is defined as \((1 - \frac{u}{v})\), where \(u\) is the residual sum of squares ((y_true - y_pred)** 2).sum()
and \(v\) is the total sum of squares ((y_true - y_true.mean()) ** 2).sum()
. The best possible score is 1.0 and it can be negative (because the model can be arbitrarily worse). A constant model that always predicts the expected value of y
, disregarding the input features, would get a \(R^2\) score of 0.0.
Test samples. For some estimators this may be a precomputed kernel matrix or a list of generic objects instead with shape (n_samples, n_samples_fitted)
, where n_samples_fitted
is the number of samples used in the fitting for the estimator.
True values for X
.
Sample weights.
\(R^2\) of self.predict(X)
w.r.t. y
.
Notes
The \(R^2\) score used when calling score
on a regressor uses multioutput='uniform_average'
from version 0.23 to keep consistent with default value of r2_score
. This influences the score
method of all the multioutput regressors (except for MultiOutputRegressor
).
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