CustomKernel.h

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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) 1999-2009 Soeren Sonnenburg
 * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society
 */

#ifndef _CUSTOMKERNEL_H___
#define _CUSTOMKERNEL_H___

#include <shogun/mathematics/Math.h>
#include <shogun/lib/common.h>
#include <shogun/kernel/Kernel.h>
#include <shogun/features/Features.h>

namespace shogun
{
class CCustomKernel: public CKernel
{
    void init(void);

    public:
        CCustomKernel();

        CCustomKernel(CKernel* k);

        CCustomKernel(SGMatrix<float64_t> km);

        virtual ~CCustomKernel();

        virtual bool dummy_init(int32_t rows, int32_t cols);

        virtual bool init(CFeatures* l, CFeatures* r);

        virtual void cleanup();

        inline virtual EKernelType get_kernel_type() { return K_CUSTOM; }

        inline virtual EFeatureType get_feature_type() { return F_ANY; }

        inline virtual EFeatureClass get_feature_class() { return C_ANY; }

        virtual const char* get_name() const { return "CustomKernel"; }

        bool set_triangle_kernel_matrix_from_triangle(
            SGVector<float64_t> tri_kernel_matrix)
        {
            return set_triangle_kernel_matrix_from_triangle_generic(tri_kernel_matrix);
        }

        template <class T>
        bool set_triangle_kernel_matrix_from_triangle_generic(
            SGVector<T> tri_kernel_matrix)
        {
            ASSERT(tri_kernel_matrix.vector);

            int64_t len = tri_kernel_matrix.vlen;
            int64_t cols = (int64_t) floor(-0.5 + CMath::sqrt(0.25+2*len));

            if (cols*(cols+1)/2 != len)
            {
                SG_ERROR("km should be a vector containing a lower triangle matrix, with len=cols*(cols+1)/2 elements\n");
                return false;
            }

            cleanup_custom();
            SG_DEBUG( "using custom kernel of size %dx%d\n", cols,cols);

            kmatrix.matrix = SG_MALLOC(float32_t, len);
            kmatrix.num_rows=cols;
            kmatrix.num_cols=cols;
            upper_diagonal=true;

            for (int64_t i=0; i<len; i++)
                kmatrix.matrix[i]=tri_kernel_matrix.vector[i];

            dummy_init(cols,cols);
            return true;
        }

        inline bool set_triangle_kernel_matrix_from_full(
            SGMatrix<float64_t> full_kernel_matrix)
        {
            return set_triangle_kernel_matrix_from_full_generic(full_kernel_matrix);
        }

        template <class T>
        bool set_triangle_kernel_matrix_from_full_generic(
            SGMatrix<T> full_kernel_matrix)
        {
            int32_t rows = full_kernel_matrix.num_rows;
            int32_t cols = full_kernel_matrix.num_cols;
            ASSERT(rows==cols);

            cleanup_custom();
            SG_DEBUG( "using custom kernel of size %dx%d\n", cols,cols);

            kmatrix.matrix = SG_MALLOC(float32_t, int64_t(rows)*cols);
            kmatrix.num_rows = rows;
            kmatrix.num_cols = cols;
            upper_diagonal = false;

            for (int64_t row=0; row<rows; row++)
            {
                for (int64_t col=row; col<cols; col++)
                {
                    int64_t idx=row * cols - row*(row+1)/2 + col;
                    kmatrix.matrix[idx] = full_kernel_matrix.matrix[col*rows+row];
                }
            }

            dummy_init(rows, cols);
            return true;
        }

        bool set_full_kernel_matrix_from_full(
            SGMatrix<float32_t> full_kernel_matrix)
        {
            cleanup_custom();
            kmatrix.matrix = full_kernel_matrix.matrix;
            kmatrix.num_rows=full_kernel_matrix.num_rows;
            kmatrix.num_cols=full_kernel_matrix.num_cols;
            dummy_init(kmatrix.num_rows, kmatrix.num_cols);
            return true;
        }

        bool set_full_kernel_matrix_from_full(
            SGMatrix<float64_t> full_kernel_matrix)
        {
            cleanup_custom();
            int32_t rows=full_kernel_matrix.num_rows;
            int32_t cols=full_kernel_matrix.num_cols;
            SG_DEBUG( "using custom kernel of size %dx%d\n", rows,cols);

            kmatrix.matrix = SG_MALLOC(float32_t, int64_t(rows)*cols);
            kmatrix.num_rows = rows;
            kmatrix.num_cols = cols;
            upper_diagonal = false;

            for (int32_t row=0; row<rows; row++)
            {
                for (int32_t col=0; col<cols; col++)
                    kmatrix.matrix[int64_t(row) * cols + col] =
                            full_kernel_matrix.matrix[int64_t(col)*rows+row];
            }

            dummy_init(rows, cols);
            return true;
        }

        virtual inline int32_t get_num_vec_lhs()
        {
            return kmatrix.num_rows;
        }

        virtual inline int32_t get_num_vec_rhs()
        {
            return kmatrix.num_cols;
        }

        virtual inline bool has_features()
        {
            return (kmatrix.num_rows>0) && (kmatrix.num_cols>0);
        }

    protected:

        inline virtual float64_t compute(int32_t row, int32_t col)
        {
            ASSERT(kmatrix.matrix);

            if (upper_diagonal)
            {
                if (row <= col)
                {
                    int64_t r=row;
                    return kmatrix.matrix[r*kmatrix.num_rows - r*(r+1)/2 + col];
                }
                else
                {
                    int64_t c=col;
                    return kmatrix.matrix[c*kmatrix.num_cols - c*(c+1)/2 + row];
                }
            }
            else
            {
                int64_t r=row;
                return kmatrix.matrix[r*kmatrix.num_cols+col];
            }
        }

    private:

        void cleanup_custom();

    protected:

        SGMatrix<float32_t> kmatrix;

        bool upper_diagonal;
};

}
#endif /* _CUSTOMKERNEL_H__ */