import warnings
import numpy as np
from .base import _fit_liblinear, BaseSVC, BaseLibSVM
from ..base import BaseEstimator, RegressorMixin
from ..linear_model.base import LinearClassifierMixin, SparseCoefMixin, \
LinearModel
from ..feature_selection.from_model import _LearntSelectorMixin
from ..utils import check_X_y
class LinearSVC(BaseEstimator, LinearClassifierMixin,
_LearntSelectorMixin, SparseCoefMixin):
"""Linear Support Vector Classification.
Similar to SVC with parameter kernel='linear', but implemented in terms of
liblinear rather than libsvm, so it has more flexibility in the choice of
penalties and loss functions and should scale better (to large numbers of
samples).
This class supports both dense and sparse input and the multiclass support
is handled according to a one-vs-the-rest scheme.
Parameters
----------
C : float, optional (default=1.0)
Penalty parameter C of the error term.
loss : string, 'hinge' or 'squared_hinge' (default='squared_hinge')
Specifies the loss function. 'hinge' is the standard SVM loss
(used e.g. by the SVC class) while 'squared_hinge' is the
square of the hinge loss.
penalty : string, 'l1' or 'l2' (default='l2')
Specifies the norm used in the penalization. The 'l2'
penalty is the standard used in SVC. The 'l1' leads to `coef_`
vectors that are sparse.
dual : bool, (default=True)
Select the algorithm to either solve the dual or primal
optimization problem. Prefer dual=False when n_samples > n_features.
tol : float, optional (default=1e-4)
Tolerance for stopping criteria.
multi_class: string, 'ovr' or 'crammer_singer' (default='ovr')
Determines the multi-class strategy if `y` contains more than
two classes.
`ovr` trains n_classes one-vs-rest classifiers, while `crammer_singer`
optimizes a joint objective over all classes.
While `crammer_singer` is interesting from an theoretical perspective
as it is consistent it is seldom used in practice and rarely leads to
better accuracy and is more expensive to compute.
If `crammer_singer` is chosen, the options loss, penalty and dual will
be ignored.
fit_intercept : boolean, optional (default=True)
Whether to calculate the intercept for this model. If set
to false, no intercept will be used in calculations
(e.g. data is expected to be already centered).
intercept_scaling : float, optional (default=1)
When self.fit_intercept is True, instance vector x becomes
[x, self.intercept_scaling],
i.e. a "synthetic" feature with constant value equals to
intercept_scaling is appended to the instance vector.
The intercept becomes intercept_scaling * synthetic feature weight
Note! the synthetic feature weight is subject to l1/l2 regularization
as all other features.
To lessen the effect of regularization on synthetic feature weight
(and therefore on the intercept) intercept_scaling has to be increased
class_weight : {dict, 'auto'}, optional
Set the parameter C of class i to class_weight[i]*C for
SVC. If not given, all classes are supposed to have
weight one. The 'auto' mode uses the values of y to
automatically adjust weights inversely proportional to
class frequencies.
verbose : int, (default=0)
Enable verbose output. Note that this setting takes advantage of a
per-process runtime setting in liblinear that, if enabled, may not work
properly in a multithreaded context.
random_state : int seed, RandomState instance, or None (default=None)
The seed of the pseudo random number generator to use when
shuffling the data.
max_iter : int, (default=1000)
The maximum number of iterations to be run.
Attributes
----------
coef_ : array, shape = [n_features] if n_classes == 2 \
else [n_classes, n_features]
Weights assigned to the features (coefficients in the primal
problem). This is only available in the case of linear kernel.
`coef_` is a readonly property derived from `raw_coef_` that \
follows the internal memory layout of liblinear.
intercept_ : array, shape = [1] if n_classes == 2 else [n_classes]
Constants in decision function.
Notes
-----
The underlying C implementation uses a random number generator to
select features when fitting the model. It is thus not uncommon,
to have slightly different results for the same input data. If
that happens, try with a smaller tol parameter.
The underlying implementation (liblinear) uses a sparse internal
representation for the data that will incur a memory copy.
Predict output may not match that of standalone liblinear in certain
cases. See :ref:`differences from liblinear <liblinear_differences>`
in the narrative documentation.
**References:**
`LIBLINEAR: A Library for Large Linear Classification
<http://www.csie.ntu.edu.tw/~cjlin/liblinear/>`__
See also
--------
SVC
Implementation of Support Vector Machine classifier using libsvm:
the kernel can be non-linear but its SMO algorithm does not
scale to large number of samples as LinearSVC does.
Furthermore SVC multi-class mode is implemented using one
vs one scheme while LinearSVC uses one vs the rest. It is
possible to implement one vs the rest with SVC by using the
:class:`sklearn.multiclass.OneVsRestClassifier` wrapper.
Finally SVC can fit dense data without memory copy if the input
is C-contiguous. Sparse data will still incur memory copy though.
sklearn.linear_model.SGDClassifier
SGDClassifier can optimize the same cost function as LinearSVC
by adjusting the penalty and loss parameters. In addition it requires
less memory, allows incremental (online) learning, and implements
various loss functions and regularization regimes.
"""
def __init__(self, penalty='l2', loss='squared_hinge', dual=True, tol=1e-4,
C=1.0, multi_class='ovr', fit_intercept=True,
intercept_scaling=1, class_weight=None, verbose=0,
random_state=None, max_iter=1000):
self.dual = dual
self.tol = tol
self.C = C
self.multi_class = multi_class
self.fit_intercept = fit_intercept
self.intercept_scaling = intercept_scaling
self.class_weight = class_weight
self.verbose = verbose
self.random_state = random_state
self.max_iter = max_iter
self.penalty = penalty
self.loss = loss
def fit(self, X, y):
"""Fit the model according to the given training data.
Parameters
----------
X : {array-like, sparse matrix}, shape = [n_samples, n_features]
Training vector, where n_samples in the number of samples and
n_features is the number of features.
y : array-like, shape = [n_samples]
Target vector relative to X
Returns
-------
self : object
Returns self.
"""
# FIXME Remove l1/l2 support in 1.0 -----------------------------------
loss_l = self.loss.lower()
msg = ("loss='%s' has been deprecated in favor of "
"loss='%s' as of 0.16. Backward compatibility"
" for the loss='%s' will be removed in %s")
# FIXME change loss_l --> self.loss after 0.18
if loss_l in ('l1', 'l2'):
old_loss = self.loss
self.loss = {'l1': 'hinge', 'l2': 'squared_hinge'}.get(loss_l)
warnings.warn(msg % (old_loss, self.loss, old_loss, '1.0'),
DeprecationWarning)
# ---------------------------------------------------------------------
if self.C < 0:
raise ValueError("Penalty term must be positive; got (C=%r)"
% self.C)
X, y = check_X_y(X, y, accept_sparse='csr',
dtype=np.float64, order="C")
self.classes_ = np.unique(y)
self.coef_, self.intercept_, self.n_iter_ = _fit_liblinear(
X, y, self.C, self.fit_intercept, self.intercept_scaling,
self.class_weight, self.penalty, self.dual, self.verbose,
self.max_iter, self.tol, self.random_state, self.multi_class,
self.loss
)
if self.multi_class == "crammer_singer" and len(self.classes_) == 2:
self.coef_ = (self.coef_[1] - self.coef_[0]).reshape(1, -1)
if self.fit_intercept:
intercept = self.intercept_[1] - self.intercept_[0]
self.intercept_ = np.array([intercept])
return self
class LinearSVR(LinearModel, RegressorMixin):
"""Linear Support Vector Regression.
Similar to SVR with parameter kernel='linear', but implemented in terms of
liblinear rather than libsvm, so it has more flexibility in the choice of
penalties and loss functions and should scale better (to large numbers of
samples).
This class supports both dense and sparse input.
Parameters
----------
C : float, optional (default=1.0)
Penalty parameter C of the error term. The penalty is a squared
l2 penalty. The bigger this parameter, the less regularization is used.
loss : string, 'epsilon_insensitive' or 'squared_epsilon_insensitive' \
(default='epsilon_insensitive')
Specifies the loss function. 'l1' is the epsilon-insensitive loss
(standard SVR) while 'l2' is the squared epsilon-insensitive loss.
epsilon : float, optional (default=0.1)
Epsilon parameter in the epsilon-insensitive loss function. Note
that the value of this parameter depends on the scale of the target
variable y. If unsure, set epsilon=0.
dual : bool, (default=True)
Select the algorithm to either solve the dual or primal
optimization problem. Prefer dual=False when n_samples > n_features.
tol : float, optional (default=1e-4)
Tolerance for stopping criteria.
fit_intercept : boolean, optional (default=True)
Whether to calculate the intercept for this model. If set
to false, no intercept will be used in calculations
(e.g. data is expected to be already centered).
intercept_scaling : float, optional (default=1)
When self.fit_intercept is True, instance vector x becomes
[x, self.intercept_scaling],
i.e. a "synthetic" feature with constant value equals to
intercept_scaling is appended to the instance vector.
The intercept becomes intercept_scaling * synthetic feature weight
Note! the synthetic feature weight is subject to l1/l2 regularization
as all other features.
To lessen the effect of regularization on synthetic feature weight
(and therefore on the intercept) intercept_scaling has to be increased.
verbose : int, (default=0)
Enable verbose output. Note that this setting takes advantage of a
per-process runtime setting in liblinear that, if enabled, may not work
properly in a multithreaded context.
random_state : int seed, RandomState instance, or None (default=None)
The seed of the pseudo random number generator to use when
shuffling the data.
max_iter : int, (default=1000)
The maximum number of iterations to be run.
Attributes
----------
coef_ : array, shape = [n_features] if n_classes == 2 \
else [n_classes, n_features]
Weights assigned to the features (coefficients in the primal
problem). This is only available in the case of linear kernel.
`coef_` is a readonly property derived from `raw_coef_` that \
follows the internal memory layout of liblinear.
intercept_ : array, shape = [1] if n_classes == 2 else [n_classes]
Constants in decision function.
See also
--------
LinearSVC
Implementation of Support Vector Machine classifier using the
same library as this class (liblinear).
SVR
Implementation of Support Vector Machine regression using libsvm:
the kernel can be non-linear but its SMO algorithm does not
scale to large number of samples as LinearSVC does.
sklearn.linear_model.SGDRegressor
SGDRegressor can optimize the same cost function as LinearSVR
by adjusting the penalty and loss parameters. In addition it requires
less memory, allows incremental (online) learning, and implements
various loss functions and regularization regimes.
"""
def __init__(self, epsilon=0.0, tol=1e-4, C=1.0,
loss='epsilon_insensitive', fit_intercept=True,
intercept_scaling=1., dual=True, verbose=0,
random_state=None, max_iter=1000):
self.tol = tol
self.C = C
self.epsilon = epsilon
self.fit_intercept = fit_intercept
self.intercept_scaling = intercept_scaling
self.verbose = verbose
self.random_state = random_state
self.max_iter = max_iter
self.dual = dual
self.loss = loss
def fit(self, X, y):
"""Fit the model according to the given training data.
Parameters
----------
X : {array-like, sparse matrix}, shape = [n_samples, n_features]
Training vector, where n_samples in the number of samples and
n_features is the number of features.
y : array-like, shape = [n_samples]
Target vector relative to X
Returns
-------
self : object
Returns self.
"""
# FIXME Remove l1/l2 support in 1.0 -----------------------------------
loss_l = self.loss.lower()
msg = ("loss='%s' has been deprecated in favor of "
"loss='%s' as of 0.16. Backward compatibility"
" for the loss='%s' will be removed in %s")
# FIXME change loss_l --> self.loss after 0.18
if loss_l in ('l1', 'l2'):
old_loss = self.loss
self.loss = {'l1': 'epsilon_insensitive',
'l2': 'squared_epsilon_insensitive'
}.get(loss_l)
warnings.warn(msg % (old_loss, self.loss, old_loss, '1.0'),
DeprecationWarning)
# ---------------------------------------------------------------------
if self.C < 0:
raise ValueError("Penalty term must be positive; got (C=%r)"
% self.C)
X, y = check_X_y(X, y, accept_sparse='csr',
dtype=np.float64, order="C")
penalty = 'l2' # SVR only accepts l2 penalty
self.coef_, self.intercept_, self.n_iter_ = _fit_liblinear(
X, y, self.C, self.fit_intercept, self.intercept_scaling,
None, penalty, self.dual, self.verbose,
self.max_iter, self.tol, self.random_state, loss=self.loss,
epsilon=self.epsilon)
self.coef_ = self.coef_.ravel()
return self
class SVC(BaseSVC):
"""C-Support Vector Classification.
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 dataset with more than a couple of 10000 samples.
The multiclass support is handled according to a one-vs-one scheme.
For details on the precise mathematical formulation of the provided
kernel functions and how `gamma`, `coef0` and `degree` affect each
other, see the corresponding section in the narrative documentation:
:ref:`svm_kernels`.
.. The narrative documentation is available at http://scikit-learn.org/
Parameters
----------
C : float, optional (default=1.0)
Penalty parameter C of the error term.
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 : float, optional (default=0.0)
Kernel coefficient for 'rbf', 'poly' and 'sigmoid'.
If gamma is 0.0 then 1/n_features will be used instead.
coef0 : float, optional (default=0.0)
Independent term in kernel function.
It is only significant in 'poly' and 'sigmoid'.
probability: boolean, optional (default=False)
Whether to enable probability estimates. This must be enabled prior
to calling `fit`, and will slow down that method.
shrinking: boolean, optional (default=True)
Whether to use the shrinking heuristic.
tol : float, optional (default=1e-3)
Tolerance for stopping criterion.
cache_size : float, optional
Specify the size of the kernel cache (in MB).
class_weight : {dict, 'auto'}, optional
Set the parameter C of class i to class_weight[i]*C for
SVC. If not given, all classes are supposed to have
weight one. The 'auto' mode uses the values of y to
automatically adjust weights inversely proportional to
class frequencies.
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.
random_state : int seed, RandomState instance, or None (default)
The seed of the pseudo random number generator to use when
shuffling the data for probability estimation.
Attributes
----------
support_ : array-like, shape = [n_SV]
Indices of support vectors.
support_vectors_ : array-like, shape = [n_SV, n_features]
Support vectors.
n_support_ : array-like, dtype=int32, shape = [n_class]
Number of support vectors for each class.
dual_coef_ : array, shape = [n_class-1, n_SV]
Coefficients of the support vector in the decision function. \
For multiclass, coefficient for all 1-vs-1 classifiers. \
The layout of the coefficients in the multiclass case is somewhat \
non-trivial. See the section about multi-class classification in the \
SVM section of the User Guide for details.
coef_ : array, shape = [n_class-1, n_features]
Weights assigned to the features (coefficients in the primal
problem). This is only available in the case of linear kernel.
`coef_` is a readonly property derived from `dual_coef_` and
`support_vectors_`.
intercept_ : array, shape = [n_class * (n_class-1) / 2]
Constants in decision function.
Examples
--------
>>> import numpy as np
>>> X = np.array([[-1, -1], [-2, -1], [1, 1], [2, 1]])
>>> y = np.array([1, 1, 2, 2])
>>> from sklearn.svm import SVC
>>> clf = SVC()
>>> clf.fit(X, y) #doctest: +NORMALIZE_WHITESPACE
SVC(C=1.0, cache_size=200, class_weight=None, coef0=0.0, degree=3,
gamma=0.0, kernel='rbf', max_iter=-1, probability=False,
random_state=None, shrinking=True, tol=0.001, verbose=False)
>>> print(clf.predict([[-0.8, -1]]))
[1]
See also
--------
SVR
Support Vector Machine for Regression implemented using libsvm.
LinearSVC
Scalable Linear Support Vector Machine for classification
implemented using liblinear. Check the See also section of
LinearSVC for more comparison element.
"""
def __init__(self, C=1.0, kernel='rbf', degree=3, gamma=0.0,
coef0=0.0, shrinking=True, probability=False,
tol=1e-3, cache_size=200, class_weight=None,
verbose=False, max_iter=-1, random_state=None):
super(SVC, self).__init__(
'c_svc', kernel, degree, gamma, coef0, tol, C, 0., 0., shrinking,
probability, cache_size, class_weight, verbose, max_iter,
random_state)
class NuSVC(BaseSVC):
"""Nu-Support Vector Classification.
Similar to SVC but uses a parameter to control the number of support
vectors.
The implementation is based on libsvm.
Parameters
----------
nu : float, optional (default=0.5)
An upper bound on the fraction of training errors and a lower
bound of the fraction of support vectors. Should be in the
interval (0, 1].
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 kernel function
is significant only in poly, rbf, sigmoid.
gamma : float, optional (default=0.0)
Kernel coefficient for rbf and poly, if gamma is 0.0 then 1/n_features
will be taken.
coef0 : float, optional (default=0.0)
Independent term in kernel function. It is only significant
in poly/sigmoid.
probability: boolean, optional (default=False)
Whether to enable probability estimates. This must be enabled prior
to calling `fit`, and will slow down that method.
shrinking: boolean, optional (default=True)
Whether to use the shrinking heuristic.
tol : float, optional (default=1e-3)
Tolerance for stopping criterion.
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.
random_state : int seed, RandomState instance, or None (default)
The seed of the pseudo random number generator to use when
shuffling the data for probability estimation.
Attributes
----------
support_ : array-like, shape = [n_SV]
Indices of support vectors.
support_vectors_ : array-like, shape = [n_SV, n_features]
Support vectors.
n_support_ : array-like, dtype=int32, shape = [n_class]
Number of support vector for each class.
dual_coef_ : array, shape = [n_class-1, n_SV]
Coefficients of the support vector in the decision function. \
For multiclass, coefficient for all 1-vs-1 classifiers. \
The layout of the coefficients in the multiclass case is somewhat \
non-trivial. See the section about multi-class classification in \
the SVM section of the User Guide for details.
coef_ : array, shape = [n_class-1, n_features]
Weights assigned to the features (coefficients in the primal
problem). This is only available in the case of linear kernel.
`coef_` is readonly property derived from `dual_coef_` and
`support_vectors_`.
intercept_ : array, shape = [n_class * (n_class-1) / 2]
Constants in decision function.
Examples
--------
>>> import numpy as np
>>> X = np.array([[-1, -1], [-2, -1], [1, 1], [2, 1]])
>>> y = np.array([1, 1, 2, 2])
>>> from sklearn.svm import NuSVC
>>> clf = NuSVC()
>>> clf.fit(X, y) #doctest: +NORMALIZE_WHITESPACE
NuSVC(cache_size=200, coef0=0.0, degree=3, gamma=0.0, kernel='rbf',
max_iter=-1, nu=0.5, probability=False, random_state=None,
shrinking=True, tol=0.001, verbose=False)
>>> print(clf.predict([[-0.8, -1]]))
[1]
See also
--------
SVC
Support Vector Machine for classification using libsvm.
LinearSVC
Scalable linear Support Vector Machine for classification using
liblinear.
"""
def __init__(self, nu=0.5, kernel='rbf', degree=3, gamma=0.0,
coef0=0.0, shrinking=True, probability=False,
tol=1e-3, cache_size=200, verbose=False, max_iter=-1,
random_state=None):
super(NuSVC, self).__init__(
'nu_svc', kernel, degree, gamma, coef0, tol, 0., nu, 0., shrinking,
probability, cache_size, None, verbose, max_iter, random_state)
class SVR(BaseLibSVM, RegressorMixin):
"""Epsilon-Support Vector Regression.
The free parameters in the model are C and epsilon.
The implementation is based on libsvm.
Parameters
----------
C : float, optional (default=1.0)
Penalty parameter C of the error term.
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.
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 kernel function
is significant only in poly, rbf, sigmoid.
gamma : float, optional (default=0.0)
Kernel coefficient for rbf and poly, if gamma is 0.0 then 1/n_features
will be taken.
coef0 : float, optional (default=0.0)
independent term in kernel function. It is only significant
in poly/sigmoid.
shrinking: boolean, optional (default=True)
Whether to use the shrinking heuristic.
tol : float, optional (default=1e-3)
Tolerance for stopping criterion.
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, shape = [n_SV]
Indices of support vectors.
support_vectors_ : array-like, shape = [nSV, 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 linear kernel.
`coef_` is readonly property derived from `dual_coef_` and
`support_vectors_`.
intercept_ : array, shape = [1]
Constants in decision function.
Examples
--------
>>> from sklearn.svm import SVR
>>> import numpy as np
>>> n_samples, n_features = 10, 5
>>> np.random.seed(0)
>>> y = np.random.randn(n_samples)
>>> X = np.random.randn(n_samples, n_features)
>>> clf = SVR(C=1.0, epsilon=0.2)
>>> clf.fit(X, y) #doctest: +NORMALIZE_WHITESPACE
SVR(C=1.0, cache_size=200, coef0=0.0, degree=3, epsilon=0.2, gamma=0.0,
kernel='rbf', max_iter=-1, shrinking=True, tol=0.001, verbose=False)
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.
"""
def __init__(self, kernel='rbf', degree=3, gamma=0.0, coef0=0.0, tol=1e-3,
C=1.0, epsilon=0.1, shrinking=True, cache_size=200,
verbose=False, max_iter=-1):
super(SVR, self).__init__(
'epsilon_svr', kernel=kernel, degree=degree, gamma=gamma,
coef0=coef0, tol=tol, C=C, nu=0., epsilon=epsilon, verbose=verbose,
shrinking=shrinking, probability=False, cache_size=cache_size,
class_weight=None, max_iter=max_iter, random_state=None)
class NuSVR(BaseLibSVM, RegressorMixin):
"""Nu Support Vector Regression.
Similar to NuSVC, for regression, uses a parameter nu to control
the number of support vectors. However, unlike NuSVC, where nu
replaces C, here nu replaces the parameter epsilon of epsilon-SVR.
The implementation is based on libsvm.
Parameters
----------
C : float, optional (default=1.0)
Penalty parameter C of the error term.
nu : float, optional
An upper bound on the fraction of training errors and a lower bound of
the fraction of support vectors. Should be in the interval (0, 1]. By
default 0.5 will be taken.
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 kernel function
is significant only in poly, rbf, sigmoid.
gamma : float, optional (default=0.0)
Kernel coefficient for rbf and poly, if gamma is 0.0 then 1/n_features
will be taken.
coef0 : float, optional (default=0.0)
Independent term in kernel function. It is only significant
in poly/sigmoid.
shrinking: boolean, optional (default=True)
Whether to use the shrinking heuristic.
tol : float, optional (default=1e-3)
Tolerance for stopping criterion.
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, shape = [n_SV]
Indices of support vectors.
support_vectors_ : array-like, shape = [nSV, 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 linear kernel.
`coef_` is readonly property derived from `dual_coef_` and
`support_vectors_`.
intercept_ : array, shape = [1]
Constants in decision function.
Examples
--------
>>> from sklearn.svm import NuSVR
>>> import numpy as np
>>> n_samples, n_features = 10, 5
>>> np.random.seed(0)
>>> y = np.random.randn(n_samples)
>>> X = np.random.randn(n_samples, n_features)
>>> clf = NuSVR(C=1.0, nu=0.1)
>>> clf.fit(X, y) #doctest: +NORMALIZE_WHITESPACE
NuSVR(C=1.0, cache_size=200, coef0=0.0, degree=3, gamma=0.0, kernel='rbf',
max_iter=-1, nu=0.1, shrinking=True, tol=0.001, verbose=False)
See also
--------
NuSVC
Support Vector Machine for classification implemented with libsvm
with a parameter to control the number of support vectors.
SVR
epsilon Support Vector Machine for regression implemented with libsvm.
"""
def __init__(self, nu=0.5, C=1.0, kernel='rbf', degree=3,
gamma=0.0, coef0=0.0, shrinking=True, tol=1e-3,
cache_size=200, verbose=False, max_iter=-1):
super(NuSVR, self).__init__(
'nu_svr', kernel=kernel, degree=degree, gamma=gamma, coef0=coef0,
tol=tol, C=C, nu=nu, epsilon=0., shrinking=shrinking,
probability=False, cache_size=cache_size, class_weight=None,
verbose=verbose, max_iter=max_iter, random_state=None)
class OneClassSVM(BaseLibSVM):
"""Unsupervised Outlier Detection.
Estimate the support of a high-dimensional distribution.
The implementation is based on libsvm.
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.
nu : float, optional
An upper bound on the fraction of training
errors and a lower bound of the fraction of support
vectors. Should be in the interval (0, 1]. By default 0.5
will be taken.
degree : int, optional (default=3)
Degree of the polynomial kernel function ('poly').
Ignored by all other kernels.
gamma : float, optional (default=0.0)
Kernel coefficient for 'rbf', 'poly' and 'sigmoid'.
If gamma is 0.0 then 1/n_features will be used instead.
coef0 : float, optional (default=0.0)
Independent term in kernel function.
It is only significant in 'poly' and 'sigmoid'.
tol : float, optional
Tolerance for stopping criterion.
shrinking: boolean, optional
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.
random_state : int seed, RandomState instance, or None (default)
The seed of the pseudo random number generator to use when
shuffling the data for probability estimation.
Attributes
----------
support_ : array-like, shape = [n_SV]
Indices of support vectors.
support_vectors_ : array-like, shape = [nSV, n_features]
Support vectors.
dual_coef_ : array, shape = [n_classes-1, n_SV]
Coefficients of the support vectors in the decision function.
coef_ : array, shape = [n_classes-1, n_features]
Weights assigned to the features (coefficients in the primal
problem). This is only available in the case of linear kernel.
`coef_` is readonly property derived from `dual_coef_` and
`support_vectors_`
intercept_ : array, shape = [n_classes-1]
Constants in decision function.
"""
def __init__(self, kernel='rbf', degree=3, gamma=0.0, coef0=0.0, tol=1e-3,
nu=0.5, shrinking=True, cache_size=200, verbose=False,
max_iter=-1, random_state=None):
super(OneClassSVM, self).__init__(
'one_class', kernel, degree, gamma, coef0, tol, 0., nu, 0.,
shrinking, False, cache_size, None, verbose, max_iter,
random_state)
def fit(self, X, y=None, sample_weight=None, **params):
"""
Detects the soft boundary of the set of samples X.
Parameters
----------
X : {array-like, sparse matrix}, shape (n_samples, n_features)
Set of samples, where n_samples is the number of samples and
n_features is the number of features.
sample_weight : array-like, shape (n_samples,)
Per-sample weights. Rescale C per sample. Higher weights
force the classifier to put more emphasis on these points.
Returns
-------
self : object
Returns self.
Notes
-----
If X is not a C-ordered contiguous array it is copied.
"""
super(OneClassSVM, self).fit(X, [], sample_weight=sample_weight,
**params)
return self