PyramidChi2.cpp

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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) 2008-2009 Alexander Binder
 * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society
 */

#include <shogun/kernel/PyramidChi2.h>
#include <shogun/lib/common.h>
#include <shogun/kernel/GaussianKernel.h>
#include <shogun/features/Features.h>
#include <shogun/io/SGIO.h>
#include <shogun/mathematics/Math.h>

using namespace shogun;

CPyramidChi2::CPyramidChi2()
: weights(NULL)
{
    // this will produce an erro in kernel computation!
    num_cells=0;
    width_computation_type=0;
    width=1;
    num_randfeats_forwidthcomputation=-1;
}

CPyramidChi2::CPyramidChi2(
    int32_t size, int32_t num_cells2,
        float64_t* weights_foreach_cell2,
        int32_t width_computation_type2,
        float64_t width2)
: CDotKernel(size), num_cells(num_cells2),weights(NULL),
width_computation_type(width_computation_type2), width(width2),
     num_randfeats_forwidthcomputation(-1)
{
    if(num_cells<=0)
        SG_ERROR("CPyramidChi2 Constructor fatal error: parameter num_cells2 NOT positive")
    weights=SG_MALLOC(float64_t, num_cells);
    if(weights_foreach_cell2)
    {
        for (int32_t i=0; i<num_cells; ++i)
            weights[i]=weights_foreach_cell2[i];
    }
    else
    {   for (int32_t i=0; i<num_cells; ++i)
            weights[i]=1;
    }

    if (width_computation_type>0 )
    {
        num_randfeats_forwidthcomputation=(int32_t)CMath::round(width);
        width=-1;
    }


}

void CPyramidChi2::cleanup()
{
    // this will produce an erro in kernel computation!
    num_cells=0;
    width_computation_type=0;
    width=1;

    num_randfeats_forwidthcomputation=-1;

    SG_FREE(weights);
    weights=NULL;

    CKernel::cleanup();
}

bool CPyramidChi2::init(CFeatures* l, CFeatures* r)
{
    CDotKernel::init(l, r);
    return init_normalizer();
}

CPyramidChi2::CPyramidChi2(
    CDenseFeatures<float64_t>* l, CDenseFeatures<float64_t>* r,
        int32_t size, int32_t num_cells2,
        float64_t* weights_foreach_cell2,
        int32_t width_computation_type2,
        float64_t width2)
: CDotKernel(size), num_cells(num_cells2), weights(NULL),
width_computation_type(width_computation_type2), width(width2),
      num_randfeats_forwidthcomputation(-1)
{
    if(num_cells<=0)
        SG_ERROR("CPyramidChi2 Constructor fatal error: parameter num_cells2 NOT positive")
    weights=SG_MALLOC(float64_t, num_cells);
    if(weights_foreach_cell2)
    {
        for (int32_t i=0; i<num_cells; ++i)
            weights[i]=weights_foreach_cell2[i];
    }
    else
    {   for (int32_t i=0; i<num_cells; ++i)
            weights[i]=1;
    }

    if (width_computation_type>0 )
    {
        num_randfeats_forwidthcomputation=(int32_t)CMath::round(width);
        width=-1;
    }

    init(l, r);
}

CPyramidChi2::~CPyramidChi2()
{
    cleanup();
}



float64_t CPyramidChi2::compute(int32_t idx_a, int32_t idx_b)
{

    if(num_cells<=0)
        SG_ERROR("CPyramidChi2::compute(...) fatal error: parameter num_cells NOT positive")

    int32_t alen, blen;
    bool afree, bfree;

    float64_t* avec=((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(idx_a,
                    alen, afree);
    float64_t* bvec=((CDenseFeatures<float64_t>*) rhs)->get_feature_vector(idx_b,
                    blen, bfree);
    if(alen!=blen)
        SG_ERROR("CPyramidChi2::compute(...) fatal error: lhs feature dim != rhs feature dim")

    int32_t dims=alen/num_cells;


    if(width<=0)
    {
        if(width_computation_type >0)
        {

            //compute width
            int32_t numind;

            if (num_randfeats_forwidthcomputation >1)
            {
                numind=CMath::min( ((CDenseFeatures<float64_t>*) lhs)->get_num_vectors() , num_randfeats_forwidthcomputation);
            }
            else
            {
                numind= ((CDenseFeatures<float64_t>*) lhs)->get_num_vectors();
            }
            float64_t* featindices = SG_MALLOC(float64_t, numind);

            if (num_randfeats_forwidthcomputation >0)
            {
                for(int32_t i=0; i< numind;++i)
                    featindices[i]=CMath::random(0, ((CDenseFeatures<float64_t>*) lhs)->get_num_vectors()-1);
            }
            else
            {
                for(int32_t i=0; i< numind;++i)
                    featindices[i]=i;
            }


            width=0;

            //get avec, get bvec    only from lhs, do not free
            for (int32_t li=0; li < numind;++li)
            {
                avec=((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(featindices[li],
                    alen, afree);
                for (int32_t ri=0; ri <=li;++ri)
                {
                    // lhs is right here!!!
                    bvec=((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(featindices[ri],
                            blen, bfree);

                    float64_t result=0;
                    for (int32_t histoind=0; histoind<num_cells; ++histoind)
                    {
                        float64_t curweight=weights[histoind];

                        for (int32_t i=0; i< dims; ++i)
                        {
                            int32_t index= histoind*dims+i;
                            if(avec[index] + bvec[index]>0)
                            {
                                result+= curweight*(avec[index] - bvec[index])*(avec[index]
                                    - bvec[index])/(avec[index] + bvec[index]);
                            }
                        }
                    }
                    width+=result*2.0/((double)numind)/(numind+1.0);
                }

            }
            SG_FREE(featindices);
        }
        else
        {
            SG_ERROR("CPyramidChi2::compute(...) fatal error: width<=0")
        }
    }


    //the actual kernel computation
    avec=((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(idx_a,
                    alen, afree);
    bvec=((CDenseFeatures<float64_t>*) rhs)->get_feature_vector(idx_b,
                    blen, bfree);

    float64_t result=0;
    for (int32_t histoind=0; histoind<num_cells; ++histoind)
    {
        float64_t curweight=weights[histoind];

        for (int32_t i=0; i< dims; ++i)
        {
            int32_t index= histoind*dims+i;
            if(avec[index] + bvec[index]>0)
            {
                result+= curweight*(avec[index] - bvec[index])*(avec[index]
                    - bvec[index])/(avec[index] + bvec[index]);
            }
        }
    }
    result= CMath::exp(-result/width);


    ((CDenseFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
    ((CDenseFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);

    return (result);
}

void CPyramidChi2::setparams_pychi2(int32_t num_cells2,
        float64_t* weights_foreach_cell2,
        int32_t width_computation_type2,
        float64_t width2)
{
    num_cells=num_cells2;
    width_computation_type=width_computation_type2;
    width=width2;
    num_randfeats_forwidthcomputation=-1;

    if(num_cells<=0)
        SG_ERROR("CPyramidChi2::setparams_pychi2(...) fatal error: parameter num_cells2 NOT positive")
    if(weights)
        SG_FREE(weights);
    weights=SG_MALLOC(float64_t, num_cells);
    if(weights_foreach_cell2)
    {
        for (int32_t i=0; i<num_cells; ++i)
            weights[i]=weights_foreach_cell2[i];
    }
    else
    {   for (int32_t i=0; i<num_cells; ++i)
            weights[i]=1;
    }

    if (width_computation_type>0 )
    {
        num_randfeats_forwidthcomputation=(int32_t)CMath::round(width);
        width=-1;
    }
}