Epsilon-Support Vector Regression.
The free parameters in the model are C and epsilon.
The implementation is based on libsvm. The fit time complexity is more than quadratic with the number of samples which makes it hard to scale to datasets with more than a couple of 10000 samples. For large datasets consider using :class:`sklearn.svm.LinearSVR` or :class:`sklearn.linear_model.SGDRegressor` instead, possibly after a :class:`sklearn.kernel_approximation.Nystroem` transformer.
Read more in the :ref:`User Guide <svm_regression>`.
Parameters ---------- kernel : string, optional (default='rbf') Specifies the kernel type to be used in the algorithm. It must be one of 'linear', 'poly', 'rbf', 'sigmoid', 'precomputed' or a callable. If none is given, 'rbf' will be used. If a callable is given it is used to precompute the kernel matrix.
degree : int, optional (default=3) Degree of the polynomial kernel function ('poly'). Ignored by all other kernels.
gamma : 'scale', 'auto'
or float, optional (default='scale') Kernel coefficient for 'rbf', 'poly' and 'sigmoid'.
- if ``gamma='scale'`` (default) is passed then it uses 1 / (n_features * X.var()) as value of gamma,
- if 'auto', uses 1 / n_features.
.. versionchanged:: 0.22 The default value of ``gamma`` changed from 'auto' to 'scale'.
coef0 : float, optional (default=0.0) Independent term in kernel function. It is only significant in 'poly' and 'sigmoid'.
tol : float, optional (default=1e-3) Tolerance for stopping criterion.
C : float, optional (default=1.0) Regularization parameter. The strength of the regularization is inversely proportional to C. Must be strictly positive. The penalty is a squared l2 penalty.
epsilon : float, optional (default=0.1) Epsilon in the epsilon-SVR model. It specifies the epsilon-tube within which no penalty is associated in the training loss function with points predicted within a distance epsilon from the actual value.
shrinking : boolean, optional (default=True) Whether to use the shrinking heuristic.
cache_size : float, optional Specify the size of the kernel cache (in MB).
verbose : bool, default: False Enable verbose output. Note that this setting takes advantage of a per-process runtime setting in libsvm that, if enabled, may not work properly in a multithreaded context.
max_iter : int, optional (default=-1) Hard limit on iterations within solver, or -1 for no limit.
Attributes ---------- support_ : array-like of shape (n_SV) Indices of support vectors.
support_vectors_ : array-like of shape (n_SV, n_features) Support vectors.
dual_coef_ : array, shape = 1, n_SV
Coefficients of the support vector in the decision function.
coef_ : array, shape = 1, n_features
Weights assigned to the features (coefficients in the primal problem). This is only available in the case of a linear kernel.
`coef_` is readonly property derived from `dual_coef_` and `support_vectors_`.
fit_status_ : int 0 if correctly fitted, 1 otherwise (will raise warning)
intercept_ : array, shape = 1
Constants in decision function.
Examples -------- >>> from sklearn.svm import SVR >>> import numpy as np >>> n_samples, n_features = 10, 5 >>> rng = np.random.RandomState(0) >>> y = rng.randn(n_samples) >>> X = rng.randn(n_samples, n_features) >>> clf = SVR(C=1.0, epsilon=0.2) >>> clf.fit(X, y) SVR(epsilon=0.2)
See also -------- NuSVR Support Vector Machine for regression implemented using libsvm using a parameter to control the number of support vectors.
LinearSVR Scalable Linear Support Vector Machine for regression implemented using liblinear.
Notes ----- **References:** `LIBSVM: A Library for Support Vector Machines <http://www.csie.ntu.edu.tw/~cjlin/papers/libsvm.pdf>`__