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/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* Written (W) 1999-2008 Soeren Sonnenburg
* Copyright (C) 1999-2008 Fraunhofer Institute FIRST and Max-Planck-Society
*/
#ifndef _LINEARSTRINGKERNEL_H___
#define _LINEARSTRINGKERNEL_H___
#include "lib/common.h"
#include "kernel/StringKernel.h"
/** kernel LinearString */
class CLinearStringKernel: public CStringKernel<CHAR>
{
public:
/** constructor
*
* @param size cache size
* @param do_rescale if rescaling shall be applied
* @param scale scaling factor
*/
CLinearStringKernel(INT size,
bool do_rescale=true, DREAL scale=1.);
/** constructor
*
* @param l features of left-hand side
* @param r features of right-hand side
* @param do_rescale if rescaling shall be applied
* @param scale scaling factor
*/
CLinearStringKernel(
CStringFeatures<CHAR>* l, CStringFeatures<CHAR>* r,
bool do_rescale=true, DREAL scale=1.);
virtual ~CLinearStringKernel();
/** initialize kernel
*
* @param l features of left-hand side
* @param r features of right-hand side
* @return if initializing was successful
*/
virtual bool init(CFeatures* l, CFeatures* r);
/** clean up kernel */
virtual void cleanup();
/** load kernel init_data
*
* @param src file to load from
* @return if loading was successful
*/
virtual bool load_init(FILE* src);
/** save kernel init_data
*
* @param dest file to save to
* @return if saving was successful
*/
virtual bool save_init(FILE* dest);
/** return what type of kernel we are
*
* @return kernel type LINEAR
*/
virtual EKernelType get_kernel_type()
{
return K_LINEAR;
}
/** return the kernel's name
*
* @return name FixedDegree
*/
virtual const CHAR* get_name()
{
return "Linear";
}
/** optimizable kernel, i.e. precompute normal vector and as phi(x) = x
* do scalar product in input space
*
* @param num_suppvec number of support vectors
* @param sv_idx support vector index
* @param alphas alphas
* @return if optimization was successful
*/
virtual bool init_optimization(INT num_suppvec, INT* sv_idx,
DREAL* alphas);
/** delete optimization
*
* @return if deleting was successful
*/
virtual bool delete_optimization();
/** compute optimized
*
* @param idx index to compute
* @return optimized value at given index
*/
virtual DREAL compute_optimized(INT idx);
/** clear normal */
virtual void clear_normal();
/** add to normal
*
* @param idx where to add
* @param weight what to add
*/
virtual void add_to_normal(INT idx, DREAL weight);
protected:
/** compute kernel function for features a and b
* idx_{a,b} denote the index of the feature vectors
* in the corresponding feature object
*
* @param idx_a index a
* @param idx_b index b
* @return computed kernel function at indices a,b
*/
virtual DREAL compute(INT idx_a, INT idx_b);
/** initialize rescaling */
virtual void init_rescale();
protected:
/** scaling factor */
double scale;
/** if rescaling shall be applied */
bool do_rescale;
/** if kernel is initialized */
bool initialized;
/** normal vector (used in case of optimized kernel) */
double* normal;
};
#endif /* _LINEARSTRINGKERNEL_H___ */
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