KernelMulticlassMachine.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) 2012 Chiyuan Zhang
 * Written (W) 2012 Heiko Strathmann
 * Copyright (C) 2012 Chiyuan Zhang
 */

#include <shogun/lib/Set.h>
#include <shogun/machine/KernelMulticlassMachine.h>

using namespace shogun;

void CKernelMulticlassMachine::store_model_features()
{
    CKernel *kernel= m_kernel;
    if (!kernel)
        SG_ERROR("%s::store_model_features(): kernel is needed to store SV "
                "features.\n", get_name());

    CFeatures* lhs=kernel->get_lhs();
    CFeatures* rhs=kernel->get_rhs();
    if (!lhs)
    {
        SG_ERROR("%s::store_model_features(): kernel lhs is needed to store "
        "SV features.\n", get_name());
    }

    /* this map will be abused as a map */
    CSet<index_t> all_sv;
    for (index_t i=0; i<m_machines->get_num_elements(); ++i)
    {
        CKernelMachine *machine=(CKernelMachine *)get_machine(i);
        for (index_t j=0; j<machine->get_num_support_vectors(); ++j)
            all_sv.add(machine->get_support_vector(j));

        SG_UNREF(machine);
    }

    /* convert map to vector of SV */
    SGVector<index_t> sv_idx(all_sv.get_num_elements());
    for (index_t i=0; i<sv_idx.vlen; ++i)
        sv_idx[i]=*all_sv.get_element_ptr(i);

    CFeatures* sv_features=lhs->copy_subset(sv_idx);

    /* now, features are replaced by concatenated SV features */
    kernel->init(sv_features, rhs);

    /* was SG_REF'ed by copy_subset */
    SG_UNREF(sv_features);

    /* now the old SV indices have to be mapped to the new features */

    /* update SV of all machines */
    for (int32_t i=0; i<m_machines->get_num_elements(); ++i)
    {
        CKernelMachine *machine=(CKernelMachine *)get_machine(i);

        /* for each machine, replace SV by index in sv_idx array */
        for (int32_t j=0; j<machine->get_num_support_vectors(); ++j)
        {
            /* get index of SV in old features */
            index_t current_sv_idx=machine->get_support_vector(j);

            /* the position of this old index in the map is the position of
             * the SV in the new features */
            index_t new_sv_idx=all_sv.index_of(current_sv_idx);

            machine->set_support_vector(j, new_sv_idx);
        }

        SG_UNREF(machine);
    }

    SG_UNREF(lhs);
    SG_UNREF(rhs);
}