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

#include "classifier/svm/LibSVMMultiClass.h"
#include "lib/io.h"

using namespace shogun;

CLibSVMMultiClass::CLibSVMMultiClass(LIBSVM_SOLVER_TYPE st)
: CMultiClassSVM(ONE_VS_ONE), model(NULL), solver_type(st)
{
}

CLibSVMMultiClass::CLibSVMMultiClass(float64_t C, CKernel* k, CLabels* lab)
: CMultiClassSVM(ONE_VS_ONE, C, k, lab), model(NULL), solver_type(LIBSVM_C_SVC)
{
}

CLibSVMMultiClass::~CLibSVMMultiClass()
{
    //SG_PRINT("deleting LibSVM\n");
}

bool CLibSVMMultiClass::train(CFeatures* data)
{
    struct svm_node* x_space;

    problem = svm_problem();

    ASSERT(labels && labels->get_num_labels());
    int32_t num_classes = labels->get_num_classes();
    problem.l=labels->get_num_labels();
    SG_INFO( "%d trainlabels, %d classes\n", problem.l, num_classes);

    if (data)
    {
        if (labels->get_num_labels() != data->get_num_vectors())
            SG_ERROR("Number of training vectors does not match number of labels\n");
        kernel->init(data, data);
    }

    problem.y=new float64_t[problem.l];
    problem.x=new struct svm_node*[problem.l];
    problem.pv=new float64_t[problem.l];
    problem.C=new float64_t[problem.l];

    x_space=new struct svm_node[2*problem.l];

    for (int32_t i=0; i<problem.l; i++)
    {
        problem.pv[i]=-1.0;
        problem.y[i]=labels->get_label(i);
        problem.x[i]=&x_space[2*i];
        x_space[2*i].index=i;
        x_space[2*i+1].index=-1;
    }

    ASSERT(kernel);

    param.svm_type=solver_type; // C SVM or NU_SVM
    param.kernel_type = LINEAR;
    param.degree = 3;
    param.gamma = 0;    // 1/k
    param.coef0 = 0;
    param.nu = get_nu(); // Nu
    param.kernel=kernel;
    param.cache_size = kernel->get_cache_size();
    param.max_train_time = max_train_time;
    param.C = get_C1();
    param.eps = epsilon;
    param.p = 0.1;
    param.shrinking = 1;
    param.nr_weight = 0;
    param.weight_label = NULL;
    param.weight = NULL;
    param.use_bias = get_bias_enabled();

    const char* error_msg = svm_check_parameter(&problem,&param);

    if(error_msg)
        SG_ERROR("Error: %s\n",error_msg);

    model = svm_train(&problem, &param);

    if (model)
    {
        ASSERT(model->nr_class==num_classes);
        ASSERT((model->l==0) || (model->l>0 && model->SV && model->sv_coef));
        create_multiclass_svm(num_classes);

        int32_t* offsets=new int32_t[num_classes];
        offsets[0]=0;

        for (int32_t i=1; i<num_classes; i++)
            offsets[i] = offsets[i-1]+model->nSV[i-1];

        int32_t s=0;
        for (int32_t i=0; i<num_classes; i++)
        {
            for (int32_t j=i+1; j<num_classes; j++)
            {
                int32_t k, l;

                float64_t sgn=1;
                if (model->label[i]>model->label[j])
                    sgn=-1;

                int32_t num_sv=model->nSV[i]+model->nSV[j];
                float64_t bias=-model->rho[s];

                ASSERT(num_sv>0);
                ASSERT(model->sv_coef[i] && model->sv_coef[j-1]);

                CSVM* svm=new CSVM(num_sv);

                svm->set_bias(sgn*bias);

                int32_t sv_idx=0;
                for (k=0; k<model->nSV[i]; k++)
                {
                    svm->set_support_vector(sv_idx, model->SV[offsets[i]+k]->index);
                    svm->set_alpha(sv_idx, sgn*model->sv_coef[j-1][offsets[i]+k]);
                    sv_idx++;
                }

                for (k=0; k<model->nSV[j]; k++)
                {
                    svm->set_support_vector(sv_idx, model->SV[offsets[j]+k]->index);
                    svm->set_alpha(sv_idx, sgn*model->sv_coef[i][offsets[j]+k]);
                    sv_idx++;
                }

                int32_t idx=0;

                if (sgn>0)
                {
                    for (k=0; k<model->label[i]; k++)
                        idx+=num_classes-k-1;

                    for (l=model->label[i]+1; l<model->label[j]; l++)
                        idx++;
                }
                else
                {
                    for (k=0; k<model->label[j]; k++)
                        idx+=num_classes-k-1;

                    for (l=model->label[j]+1; l<model->label[i]; l++)
                        idx++;
                }


//              if (sgn>0)
//                  idx=((num_classes-1)*model->label[i]+model->label[j])/2;
//              else
//                  idx=((num_classes-1)*model->label[j]+model->label[i])/2;
//
                SG_DEBUG("svm[%d] has %d sv (total: %d), b=%f label:(%d,%d) -> svm[%d]\n", s, num_sv, model->l, bias, model->label[i], model->label[j], idx);

                set_svm(idx, svm);
                s++;
            }
        }

        CSVM::set_objective(model->objective);

        delete[] offsets;
        delete[] problem.x;
        delete[] problem.y;
        delete[] x_space;

        svm_destroy_model(model);
        model=NULL;

        return true;
    }
    else
        return false;
}