DomainAdaptationSVM.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) 2007-2011 Christian Widmer
 * Copyright (C) 2007-2011 Max-Planck-Society
 */

#include <shogun/lib/config.h>

#ifdef USE_SVMLIGHT

#include <shogun/transfer/domain_adaptation/DomainAdaptationSVM.h>
#include <shogun/io/SGIO.h>
#include <shogun/labels/Labels.h>
#include <shogun/labels/BinaryLabels.h>
#include <shogun/labels/RegressionLabels.h>
#include <iostream>
#include <vector>

using namespace shogun;

CDomainAdaptationSVM::CDomainAdaptationSVM() : CSVMLight()
{
}

CDomainAdaptationSVM::CDomainAdaptationSVM(float64_t C, CKernel* k, CLabels* lab, CSVM* pre_svm, float64_t B_param) : CSVMLight(C, k, lab)
{
    init();
    init(pre_svm, B_param);
}

CDomainAdaptationSVM::~CDomainAdaptationSVM()
{
    SG_UNREF(presvm);
    SG_DEBUG("deleting DomainAdaptationSVM\n");
}


void CDomainAdaptationSVM::init(CSVM* pre_svm, float64_t B_param)
{
    // increase reference counts
    SG_REF(pre_svm);

    this->presvm=pre_svm;
    this->B=B_param;
    this->train_factor=1.0;

    // set bias of parent svm to zero
    this->presvm->set_bias(0.0);

    // invoke sanity check
    is_presvm_sane();
}

bool CDomainAdaptationSVM::is_presvm_sane()
{
    if (!presvm) {
        SG_ERROR("presvm is null");
    }

    if (presvm->get_num_support_vectors() == 0) {
        SG_ERROR("presvm has no support vectors, please train first");
    }

    if (presvm->get_bias() != 0) {
        SG_ERROR("presvm bias not set to zero");
    }

    if (presvm->get_kernel()->get_kernel_type() != this->get_kernel()->get_kernel_type()) {
        SG_ERROR("kernel types do not agree");
    }

    if (presvm->get_kernel()->get_feature_type() != this->get_kernel()->get_feature_type()) {
        SG_ERROR("feature types do not agree");
    }

    return true;
}


bool CDomainAdaptationSVM::train_machine(CFeatures* data)
{

    if (data)
    {
        if (m_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);
    }

    if (m_labels->get_label_type() != LT_BINARY)
        SG_ERROR("DomainAdaptationSVM requires binary labels\n");

    int32_t num_training_points = get_labels()->get_num_labels();
    CBinaryLabels* labels = (CBinaryLabels*) get_labels();

    float64_t* lin_term = SG_MALLOC(float64_t, num_training_points);

    // grab current training features
    CFeatures* train_data = get_kernel()->get_lhs();

    // bias of parent SVM was set to zero in constructor, already contains B
    CBinaryLabels* parent_svm_out = presvm->apply_binary(train_data);

    // pre-compute linear term
    for (int32_t i=0; i<num_training_points; i++)
    {
        lin_term[i] = train_factor * B * labels->get_label(i) * parent_svm_out->get_label(i) - 1.0;
    }

    //set linear term for QP
    this->set_linear_term(SGVector<float64_t>(lin_term, num_training_points));

    //train SVM
    bool success = CSVMLight::train_machine();
    SG_UNREF(labels);

    ASSERT(presvm)

    return success;

}


CSVM* CDomainAdaptationSVM::get_presvm()
{
    SG_REF(presvm);
    return presvm;
}


float64_t CDomainAdaptationSVM::get_B()
{
    return B;
}


float64_t CDomainAdaptationSVM::get_train_factor()
{
    return train_factor;
}


void CDomainAdaptationSVM::set_train_factor(float64_t factor)
{
    train_factor = factor;
}


CBinaryLabels* CDomainAdaptationSVM::apply_binary(CFeatures* data)
{
    ASSERT(data);
    ASSERT(presvm->get_bias()==0.0);

    int32_t num_examples = data->get_num_vectors();

    CBinaryLabels* out_current = CSVMLight::apply_binary(data);

    // recursive call if used on DomainAdaptationSVM object
    CBinaryLabels* out_presvm = presvm->apply_binary(data);

    // combine outputs
    SGVector<float64_t> out_combined(num_examples);
    for (int32_t i=0; i<num_examples; i++)
    {
        out_combined[i] = out_current->get_confidence(i) + B*out_presvm->get_confidence(i);
    }
    SG_UNREF(out_current);
    SG_UNREF(out_presvm);

    return new CBinaryLabels(out_combined);

}

void CDomainAdaptationSVM::init()
{
    presvm = NULL;
    B = 0;
    train_factor = 1.0;

    m_parameters->add((CSGObject**) &presvm, "presvm",
                      "SVM to regularize against.");
    m_parameters->add(&B, "B", "regularization parameter B.");
    m_parameters->add(&train_factor,
            "train_factor", "flag to switch off regularization in training.");
}

#endif //USE_SVMLIGHT