slope::Slope Class Reference

The SLOPE model. More...

#include <slope.h>

Public Member Functions
	Slope ()
void	setSolver (const std::string &solver)
	Sets the numerical solver used to fit the model.
void	setIntercept (bool intercept)
	Sets the intercept flag.
void	setNormalization (const std::string &type)
	Sets normalization type for the design matrix.
void	setUpdateClusters (bool update_clusters)
	Sets the update clusters flag.
void	setReturnClusters (const bool return_clusters)
	Sets the update clusters flag.
void	setAlphaMinRatio (double alpha_min_ratio)
	Sets the alpha min ratio.
void	setAlphaType (const std::string &alpha_type)
	Sets the alpha type.
void	setLearningRateDecr (double learning_rate_decr)
	Sets the learning rate decrement.
void	setQ (double q)
	Sets the q value.
void	setOscarParameters (const double theta1, const double theta2)
	Sets OSCAR parameters.
void	setTol (double tol)
	Sets the tolerance value.
void	setMaxIterations (int max_it)
	Sets the maximum number of iterations.
void	setPathLength (int path_length)
	Sets the path length.
void	setHybridCdIterations (int cd_iterations)
	Sets the frequence of proximal gradient descent steps.
void	setLambdaType (const std::string &lambda_type)
	Sets the lambda type for regularization weights.
void	setLoss (const std::string &loss_type)
	Sets the loss function type.
void	setScreening (const std::string &screening_type)
	Sets the type of feature screening used, which discards predictors that are unlikely to be active.
void	setModifyX (const bool modify_x)
	Controls if x should be modified-in-place.
void	setDevChangeTol (const double dev_change_tol)
	Sets tolerance in deviance change for early stopping.
void	setDevRatioTol (const double dev_ratio_tol)
	Sets tolerance in deviance change for early stopping.
void	setMaxClusters (const int max_clusters)
	Sets tolerance in deviance change for early stopping.
void	setCentering (const std::string &type)
	Sets the center points for feature normalization.
void	setCentering (const Eigen::VectorXd &x_centers)
	Sets the center points for feature normalization.
void	setScaling (const std::string &type)
	Sets the scaling type.
void	setDiagnostics (const bool collect_diagnostics)
	Toggles collection of diagnostics.
void	setScaling (const Eigen::VectorXd &x_scales)
	Sets the scaling factors for feature normalization.
void	setAlphaEstimationMaxIterations (const int alpha_est_maxit)
	Sets the maximum number of iterations for the alpha estimation procedure.
int	getAlphaEstimationMaxIterations () const
	Gets the maximum number of iterations allowed for the alpha estimation procedure.
bool	getFitIntercept () const
	Returns the intercept flag.
const std::string &	getLossType ()
	Get currently defined loss type.
template<typename T >
SlopePath	path (T &x, const Eigen::MatrixXd &y_in, Eigen::ArrayXd alpha=Eigen::ArrayXd::Zero(0), Eigen::ArrayXd lambda=Eigen::ArrayXd::Zero(0))
	Computes SLOPE regression solution path for multiple alpha and lambda values.
template<typename T >
SlopeFit	fit (T &x, const Eigen::MatrixXd &y_in, const double alpha=1.0, Eigen::ArrayXd lambda=Eigen::ArrayXd::Zero(0))
	Fits a single SLOPE regression model for given alpha and lambda values.

Detailed Description

The SLOPE model.

This class implements the SLOPE algorithm for regularized regression problems. It supports different loss functions (quadratic, logistic, poisson) and provides functionality for fitting models with sorted L1 regularization along a path of regularization parameters.

Definition at line 28 of file slope.h.

Constructor & Destructor Documentation

Slope()

slope::Slope::Slope ( )

inline

Default constructor for the Slope class.

Initializes the Slope object with default parameter values.

Definition at line 36 of file slope.h.

Member Function Documentation

fit()

template<typename T >

SlopeFit slope::Slope::fit	(	T &	x,
		const Eigen::MatrixXd &	y_in,
		const double	alpha = 1.0,
		Eigen::ArrayXd	lambda = Eigen::ArrayXd::Zero(0)
	)

Fits a single SLOPE regression model for given alpha and lambda values.

Template Parameters

T	Matrix type for feature input (supports dense or sparse matrices)

Parameters

x	Feature matrix of size n x p
y_in	Response matrix of size n x m
alpha	Mixing parameter for elastic net regularization
lambda	Vector of regularization parameters (if empty, computed automatically)

Returns

SlopeFit Object containing fitted model and optimization metrics

Fits a single SLOPE model with specified regularization parameters, returning coefficients and optimization details in a SlopeFit object.

Definition at line 322 of file slope.cpp.

getAlphaEstimationMaxIterations()

int slope::Slope::getAlphaEstimationMaxIterations

(

)

const

Gets the maximum number of iterations allowed for the alpha estimation procedure.

Definition at line 568 of file slope.cpp.

getFitIntercept()

bool slope::Slope::getFitIntercept

(

)

const

Returns the intercept flag.

Definition at line 574 of file slope.cpp.

getLossType()

const std::string & slope::Slope::getLossType

(

)

Get currently defined loss type.

Returns

The loss type

Definition at line 580 of file slope.cpp.

path()

template<typename T >

SlopePath slope::Slope::path	(	T &	x,
		const Eigen::MatrixXd &	y_in,
		Eigen::ArrayXd	alpha = Eigen::ArrayXd::Zero(0),
		Eigen::ArrayXd	lambda = Eigen::ArrayXd::Zero(0)
	)

Computes SLOPE regression solution path for multiple alpha and lambda values.

Template Parameters

T	Matrix type for feature input (supports dense or sparse matrices)

Parameters

x	Feature matrix of size n x p
y_in	Response matrix of size n x m
alpha	Sequence of mixing parameters for elastic net regularization
lambda	Sequence of regularization parameters (if empty, computed automatically)

Returns

SlopePath object containing full solution path and optimization metrics

Fits SLOPE models for each combination of alpha and lambda values, storing all solutions and optimization metrics in a SlopePath object.

Definition at line 27 of file slope.cpp.

setAlphaEstimationMaxIterations()

void slope::Slope::setAlphaEstimationMaxIterations

(

const int

alpha_est_maxit

)

Sets the maximum number of iterations for the alpha estimation procedure.

The current stopping criterion for this solver is that the sets of selected features between two consecutive iterations is identical, but users have experienced instances where these sets will cycle back on forth between two sets, which would make the algorithm fail to converge.

Parameters

alpha_est_maxit

The maximum number of allowed iterations

Definition at line 562 of file slope.cpp.

setAlphaMinRatio()

void slope::Slope::setAlphaMinRatio

(

double

alpha_min_ratio

)

Sets the alpha min ratio.

Parameters

alpha_min_ratio

The value to set for the alpha min ratio. A negative value means that the program automatically chooses 1e-4 if the number of observations is larger than the number of features and 1e-2 otherwise.

Definition at line 417 of file slope.cpp.

setAlphaType()

void slope::Slope::setAlphaType

(

const std::string &

alpha_type

)

Sets the alpha type.

If "path", values of "alpha" are automatically selected to span a range from completele penalization to the almost-unpenalized case: the SLOPE path. If "estimate", which is only available for the quadratic loss, the alpha value is estimated by using the scaled L2 norm of the residuals vector from an OLS fit. In case the number of features exceeds the number of observations plus 30, then this is done iteratively starting at the null (or intercept-only) models, and proceeding by refitting slope with these estimations until the set of selected features no longer changes.

Parameters

alpha_type

The type of alpha, one of "path" and "estimate".

Definition at line 410 of file slope.cpp.

setCentering() [1/2]

void slope::Slope::setCentering

(

const Eigen::VectorXd &

x_centers

)

Sets the center points for feature normalization.

Parameters

x_centers

Vector containing center values for each feature Used in feature normalization: x_normalized = (x - center) / scale

Definition at line 376 of file slope.cpp.

setCentering() [2/2]

void slope::Slope::setCentering

(

const std::string &

type

)

Sets the center points for feature normalization.

Parameters

type	Type of centering, one of: "mean", "none"

Definition at line 369 of file slope.cpp.

setDevChangeTol()

void slope::Slope::setDevChangeTol

(

const double

dev_change_tol

)

Sets tolerance in deviance change for early stopping.

Parameters

dev_change_tol

The tolerance for the change in deviance.

Definition at line 526 of file slope.cpp.

setDevRatioTol()

void slope::Slope::setDevRatioTol

(

const double

dev_ratio_tol

)

Sets tolerance in deviance change for early stopping.

Parameters

dev_ratio_tol

The tolerance for the dev ratio. If the deviance exceeds this value, the path will terminate.

Definition at line 536 of file slope.cpp.

setDiagnostics()

void slope::Slope::setDiagnostics

(

const bool

collect_diagnostics

)

Toggles collection of diagnostics.

Parameters

collect_diagnostics

Whether to collect diagnostics, i.e. dual gap, objective value, etc. These will be stored in the SlopeFit and SlopePath objects.

Definition at line 556 of file slope.cpp.

setHybridCdIterations()

void slope::Slope::setHybridCdIterations

(

int

cd_iterations

)

Sets the frequence of proximal gradient descent steps.

Parameters

cd_iterations

Number of inner coordinate descent iterations to perform in each iteration of the hybrid solver. If set to 0, the solver will resolve into pure PGD.

Definition at line 486 of file slope.cpp.

setIntercept()

void slope::Slope::setIntercept

(

bool

intercept

)

Sets the intercept flag.

Parameters

intercept

Should an intercept be fitted?

Definition at line 342 of file slope.cpp.

setLambdaType()

void slope::Slope::setLambdaType

(

const std::string &

lambda_type

)

Sets the lambda type for regularization weights.

Parameters

lambda_type

The method used to compute regularization weights. Currently "bh" (Benjamini-Hochberg), "quadratic", "oscar", and "lasso" are supported.

Definition at line 495 of file slope.cpp.

setLearningRateDecr()

void slope::Slope::setLearningRateDecr

(

double

learning_rate_decr

)

Sets the learning rate decrement.

Parameters

learning_rate_decr

The value to set for the learning rate decrement for the proximal gradient descent step.

Definition at line 426 of file slope.cpp.

setLoss()

void slope::Slope::setLoss

(

const std::string &

loss_type

)

Sets the loss function type.

Parameters

loss_type

The type of loss function to use. Supported values are: "quadratic": Quadratic regression "logistic": Logistic regression "poisson": Poisson regression "multinomial": Multinomial logistic regression

Definition at line 504 of file slope.cpp.

setMaxClusters()

void slope::Slope::setMaxClusters

(

const int

max_clusters

)

Sets tolerance in deviance change for early stopping.

Parameters

max_clusters

The maximum number of clusters. SLOPE can (theoretically) select at most select min(n, p) clusters (unique non-zero betas). By default, this is set to -1, which means that the number of clusters will be automatically set to the number of observations + 1.

Definition at line 546 of file slope.cpp.

setMaxIterations()

void slope::Slope::setMaxIterations

(

int

max_it

)

Sets the maximum number of iterations.

Parameters

max_it

The value to set for the maximum number of iterations. Must be positive. If negative (the default), then the value will be decided by the solver.

Definition at line 468 of file slope.cpp.

setModifyX()

void slope::Slope::setModifyX

(

const bool

modify_x

)

Controls if x should be modified-in-place.

If true, then x will be modified in place if it is normalized. In case when x is dense, it will be both centered and scaled. If x is sparse, it will be only scaled.

Parameters

modify_x

Whether to modfiy x in place or not

Definition at line 520 of file slope.cpp.

setNormalization()

void slope::Slope::setNormalization

(

const std::string &

type

)

Sets normalization type for the design matrix.

Parameters

type	Type of normalization: one of "standardization" or "none".

See also

setCentering() For setting centers, specifically

setScaling() For setting scales, specifically

Definition at line 348 of file slope.cpp.

setOscarParameters()

void slope::Slope::setOscarParameters	(	const double	theta1,
		const double	theta2
	)

Sets OSCAR parameters.

Parameters

theta1	Parameter for OSCAR.
theta2	Parameter for OSCAR.

Definition at line 444 of file slope.cpp.

setPathLength()

void slope::Slope::setPathLength

(

int

path_length

)

Sets the path length.

Parameters

path_length

The value to set for the path length.

Definition at line 477 of file slope.cpp.

setQ()

void slope::Slope::setQ

(

double

q

)

Sets the q value.

Parameters

q	The value to set for the q value for use in automatically generating the lambda sequence. values between 0 and 1 are allowed..

Definition at line 435 of file slope.cpp.

setReturnClusters()

void slope::Slope::setReturnClusters

(

const bool

return_clusters

)

Sets the update clusters flag.

Parameters

return_clusters

Selects whether the fitted model should return cluster information.

Definition at line 404 of file slope.cpp.

setScaling() [1/2]

void slope::Slope::setScaling

(

const Eigen::VectorXd &

x_scales

)

Sets the scaling factors for feature normalization.

Parameters

x_scales

Vector containing scale values for each feature Used in feature normalization: x_normalized = (x - center) / scale

Definition at line 391 of file slope.cpp.

setScaling() [2/2]

void slope::Slope::setScaling

(

const std::string &

type

)

Sets the scaling type.

Parameters

type	Type of scaling, one of: "sd", "l1", "none"

Definition at line 383 of file slope.cpp.

setScreening()

void slope::Slope::setScreening

(

const std::string &

screening_type

)

Sets the type of feature screening used, which discards predictors that are unlikely to be active.

Parameters

screening_type

Type of screening. Supported values are: are: "strong": Strong screening rule () "none": No screening

Definition at line 513 of file slope.cpp.

setSolver()

void slope::Slope::setSolver

(

const std::string &

solver

)

Sets the numerical solver used to fit the model.

Parameters

solver

One of "auto", "pgd", "fista", or "hybrid". In the first case (the default), the solver is automatically selected based on availability of the hybrid solver, which currently means that the hybrid solver is used everywhere except for the multinomial loss.

Definition at line 335 of file slope.cpp.

setTol()

void slope::Slope::setTol

(

double

tol

)

Sets the tolerance value.

Parameters

tol	The value to set for the tolerance value. Must be positive.

Definition at line 459 of file slope.cpp.

setUpdateClusters()

void slope::Slope::setUpdateClusters

(

bool

update_clusters

)

Sets the update clusters flag.

Parameters

update_clusters

Selects whether the coordinate descent keeps the clusters updated.

Definition at line 398 of file slope.cpp.

---

The documentation for this class was generated from the following files:

• src/slope/slope.h
• src/slope/slope.cpp