RegulatoryModulesStringKernel.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) 2009 Sebastian J. Schultheiss and Soeren Sonnenburg
 * Copyright (C) 2009 Max-Planck-Society
 */

#include <shogun/lib/common.h>
#include <shogun/kernel/RegulatoryModulesStringKernel.h>
#include <shogun/features/Features.h>
#include <shogun/features/SimpleFeatures.h>
#include <shogun/io/SGIO.h>

using namespace shogun;

CRegulatoryModulesStringKernel::CRegulatoryModulesStringKernel()
: CStringKernel<char>(0), width(0.0), degree(0), shift(0), window(0),
    motif_positions_lhs(NULL), motif_positions_rhs(NULL),
  position_weights(NULL), weights(NULL)
{
    register_params();
}

CRegulatoryModulesStringKernel::CRegulatoryModulesStringKernel(
        int32_t size, float64_t w, int32_t d, int32_t s, int32_t wl)
: CStringKernel<char>(size), width(w), degree(d), shift(s), window(wl), 
    motif_positions_lhs(NULL), motif_positions_rhs(NULL), position_weights(NULL), weights(NULL)
{
    register_params();
}

CRegulatoryModulesStringKernel::CRegulatoryModulesStringKernel(CStringFeatures<char>* lstr, CStringFeatures<char>* rstr, 
        CSimpleFeatures<uint16_t>* lpos, CSimpleFeatures<uint16_t>* rpos, 
        float64_t w, int32_t d, int32_t s, int32_t wl, int32_t size)
: CStringKernel<char>(size), width(w), degree(d), shift(s), window(wl),
    motif_positions_lhs(NULL), motif_positions_rhs(NULL), position_weights(NULL), weights(NULL)
{
    set_motif_positions(lpos, rpos);
    init(lstr,rstr);
    register_params();
}

CRegulatoryModulesStringKernel::~CRegulatoryModulesStringKernel()
{
    SG_UNREF(motif_positions_lhs);
    SG_UNREF(motif_positions_rhs);
}

bool CRegulatoryModulesStringKernel::init(CFeatures* l, CFeatures* r)
{
    ASSERT(motif_positions_lhs);
    ASSERT(motif_positions_rhs);
    
    if (l->get_num_vectors() != motif_positions_lhs->get_num_vectors())
        SG_ERROR("Number of vectors does not agree (LHS: %d, Motif LHS: %d).\n", 
                l->get_num_vectors(),  motif_positions_lhs->get_num_vectors());
    if (r->get_num_vectors() != motif_positions_rhs->get_num_vectors())
        SG_ERROR("Number of vectors does not agree (RHS: %d, Motif RHS: %d).\n",
                r->get_num_vectors(), motif_positions_rhs->get_num_vectors());
    
    set_wd_weights();
    CStringKernel<char>::init(l, r);
    return init_normalizer();
}

void CRegulatoryModulesStringKernel::set_motif_positions(
        CSimpleFeatures<uint16_t>* positions_lhs, CSimpleFeatures<uint16_t>* positions_rhs)
{
    ASSERT(positions_lhs);
    ASSERT(positions_rhs);
    SG_UNREF(motif_positions_lhs);
    SG_UNREF(motif_positions_rhs);
    if (positions_lhs->get_num_features() != positions_rhs->get_num_features())
        SG_ERROR("Number of dimensions does not agree.\n");
        
    motif_positions_lhs=positions_lhs;
    motif_positions_rhs=positions_rhs;
    SG_REF(positions_lhs);
    SG_REF(positions_rhs);
}

float64_t CRegulatoryModulesStringKernel::compute(int32_t idx_a, int32_t idx_b)
{
    ASSERT(motif_positions_lhs);
    ASSERT(motif_positions_rhs);

    bool free_avec, free_bvec;
    char* avec=((CStringFeatures<char>*) lhs)->get_feature_vector(idx_a, alen, free_avec);
    char* bvec=((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen, free_bvec);

    int32_t alen_pos, blen_pos;
    bool afree_pos, bfree_pos;
    uint16_t* positions_a = motif_positions_lhs->get_feature_vector(idx_a, alen_pos, afree_pos);
    uint16_t* positions_b = motif_positions_rhs->get_feature_vector(idx_b, blen_pos, bfree_pos);
    ASSERT(alen_pos==blen_pos);
    int32_t num_pos=alen_pos;


    float64_t result_rbf=0;
    float64_t result_wds=0;

    for (int32_t p=0; p<num_pos; p++)
    {       
        result_rbf+=CMath::sq(positions_a[p]-positions_b[p]);

        for (int32_t p2=0; p2<num_pos; p2++) //p+1 and below * 2
            result_rbf+=CMath::sq( (positions_a[p]-positions_a[p2]) - (positions_b[p]-positions_b[p2]) );
        
        int32_t limit = window;
        if (window + positions_a[p] > alen)
            limit = alen - positions_a[p];

        if (window + positions_b[p] > blen)
            limit = CMath::min(limit, blen - positions_b[p]);
        
        result_wds+=compute_wds(&avec[positions_a[p]], &bvec[positions_b[p]],
                limit);
    }
    
    float64_t result=exp(-result_rbf/width)+result_wds;

    ((CStringFeatures<char>*) lhs)->free_feature_vector(avec, idx_a, free_avec);
    ((CStringFeatures<char>*) rhs)->free_feature_vector(bvec, idx_b, free_bvec);
    ((CSimpleFeatures<uint16_t>*) lhs)->free_feature_vector(positions_a, idx_a, afree_pos);
    ((CSimpleFeatures<uint16_t>*) rhs)->free_feature_vector(positions_b, idx_b, bfree_pos);

    return result;
}

float64_t CRegulatoryModulesStringKernel::compute_wds(
    char* avec, char* bvec, int32_t len)
{
    float64_t* max_shift_vec = SG_MALLOC(float64_t, shift);
    float64_t sum0=0 ;
    for (int32_t i=0; i<shift; i++)
        max_shift_vec[i]=0 ;

    // no shift
    for (int32_t i=0; i<len; i++)
    {
        if ((position_weights!=NULL) && (position_weights[i]==0.0))
            continue ;

        float64_t sumi = 0.0 ;
        for (int32_t j=0; (j<degree) && (i+j<len); j++)
        {
            if (avec[i+j]!=bvec[i+j])
                break ;
            sumi += weights[j];
        }
        if (position_weights!=NULL)
            sum0 += position_weights[i]*sumi ;
        else
            sum0 += sumi ;
    } ;

    for (int32_t i=0; i<len; i++)
    {
        for (int32_t k=1; (k<=shift) && (i+k<len); k++)
        {
            if ((position_weights!=NULL) && (position_weights[i]==0.0) && (position_weights[i+k]==0.0))
                continue ;

            float64_t sumi1 = 0.0 ;
            // shift in sequence a
            for (int32_t j=0; (j<degree) && (i+j+k<len); j++)
            {
                if (avec[i+j+k]!=bvec[i+j])
                    break ;
                sumi1 += weights[j];
            }
            float64_t sumi2 = 0.0 ;
            // shift in sequence b
            for (int32_t j=0; (j<degree) && (i+j+k<len); j++)
            {
                if (avec[i+j]!=bvec[i+j+k])
                    break ;
                sumi2 += weights[j];
            }
            if (position_weights!=NULL)
                max_shift_vec[k-1] += position_weights[i]*sumi1 + position_weights[i+k]*sumi2 ;
            else
                max_shift_vec[k-1] += sumi1 + sumi2 ;
        } ;
    }

    float64_t result = sum0 ;
    for (int32_t i=0; i<shift; i++)
        result += max_shift_vec[i]/(2*(i+1)) ;

    SG_FREE(max_shift_vec);
    return result ;
}

void CRegulatoryModulesStringKernel::set_wd_weights()
{
    ASSERT(degree>0);

    SG_FREE(weights);
    weights=SG_MALLOC(float64_t, degree);
        
    int32_t i;
    float64_t sum=0;
    for (i=0; i<degree; i++)
    {
        weights[i]=degree-i;    
        sum+=weights[i];
    }
    
    for (i=0; i<degree; i++)
        weights[i]/=sum;
}

void CRegulatoryModulesStringKernel::register_params()
{
    m_parameters->add(&width, "width", "the width of Gaussian kernel part");
    m_parameters->add(&degree, "degree", "the degree of weighted degree kernel part");
    m_parameters->add(&shift, "shift", "the shift of weighted degree with shifts kernel part");
    m_parameters->add(&window, "window", "the size of window around motifs");
    m_parameters->add_vector((CSGObject***)&motif_positions_lhs, &alen, "motif_positions_lhs", "the matrix of motif positions from sequences left-hand side");
    m_parameters->add_vector((CSGObject***)&motif_positions_rhs, &blen, "motif_positions_rhs", "the matrix of motif positions from sequences right-hand side");
    m_parameters->add_vector(&position_weights, &degree, "position_weights", "scaling weights in window");
    m_parameters->add_vector(&weights, &degree, "weights", "weights of WD kernel");
}