Kernel Class Reference

Inheritance diagram for Kernel:

Collaboration diagram for Kernel:

Public Member Functions
	Kernel (int l, svm_node *const *x, const svm_parameter &param)
virtual	~Kernel ()
virtual Qfloat *	get_Q (int column, int len) const =0
virtual double *	get_QD () const =0
virtual void	swap_index (int i, int j) const
Public Member Functions inherited from QMatrix
virtual	~QMatrix ()

Static Public Member Functions
static double	k_function (const svm_node *x, const svm_node *y, const svm_parameter &param)

Protected Attributes
double(Kernel::*	kernel_function )(int i, int j) const

Detailed Description

Definition at line 208 of file svm.cpp.

Constructor & Destructor Documentation

Kernel()

Kernel::Kernel	(	int	l,
		svm_node *const *	x,
		const svm_parameter &	param
	)

Definition at line 259 of file svm.cpp.

:kernel_type(param.kernel_type), degree(param.degree),
 gamma(param.gamma), coef0(param.coef0)
{
    switch(kernel_type)
    {
        case LINEAR:
            kernel_function = &Kernel::kernel_linear;
            break;
        case POLY:
            kernel_function = &Kernel::kernel_poly;
            break;
        case RBF:
            kernel_function = &Kernel::kernel_rbf;
            break;
        case SIGMOID:
            kernel_function = &Kernel::kernel_sigmoid;
            break;
        case PRECOMPUTED:
            kernel_function = &Kernel::kernel_precomputed;
            break;
    }

    clone(x,x_,l);

    if(kernel_type == RBF)
    {
        x_square = new double[l];
        for(int i=0;i<l;i++)
            x_square[i] = dot(x[i],x[i]);
    }
    else
        x_square = 0;
}

~Kernel()

Kernel::~Kernel ( )

virtual

Definition at line 294 of file svm.cpp.

{
    delete[] x;
    delete[] x_square;
}

Member Function Documentation

get_Q()

virtual Qfloat* Kernel::get_Q ( int  column, int  len  ) const

pure virtual

Implements QMatrix.

Implemented in SVR_Q, ONE_CLASS_Q, and SVC_Q.

get_QD()

virtual double* Kernel::get_QD ( ) const

pure virtual

Implements QMatrix.

Implemented in SVR_Q, ONE_CLASS_Q, and SVC_Q.

k_function()

double Kernel::k_function ( const svm_node *  x, const svm_node *  y, const svm_parameter &  param  )

static

Definition at line 322 of file svm.cpp.

{
    switch(param.kernel_type)
    {
        case LINEAR:
            return dot(x,y);
        case POLY:
            return powi(param.gamma*dot(x,y)+param.coef0,param.degree);
        case RBF:
        {
            double sum = 0;
            while(x->index != -1 && y->index !=-1)
            {
                if(x->index == y->index)
                {
                    double d = x->value - y->value;
                    sum += d*d;
                    ++x;
                    ++y;
                }
                else
                {
                    if(x->index > y->index)
                    {
                        sum += y->value * y->value;
                        ++y;
                    }
                    else
                    {
                        sum += x->value * x->value;
                        ++x;
                    }
                }
            }

            while(x->index != -1)
            {
                sum += x->value * x->value;
                ++x;
            }

            while(y->index != -1)
            {
                sum += y->value * y->value;
                ++y;
            }

            return exp(-param.gamma*sum);
        }
        case SIGMOID:
            return tanh(param.gamma*dot(x,y)+param.coef0);
        case PRECOMPUTED:  //x: test (validation), y: SV
            return x[(int)(y->value)].value;
        default:
            return 0;  // Unreachable
    }
}

swap_index()

virtual void Kernel::swap_index ( int  i, int  j  ) const

inlinevirtual

Implements QMatrix.

Reimplemented in SVR_Q, ONE_CLASS_Q, and SVC_Q.

Definition at line 217 of file svm.cpp.

    {
        swap(x[i],x[j]);
        if(x_square) swap(x_square[i],x_square[j]);
    }

Member Data Documentation

kernel_function

double(Kernel::* Kernel::kernel_function) (int i, int j) const

protected

Definition at line 224 of file svm.cpp.

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

• libsvm/svm.cpp