ClusteringEvaluation.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
 * Copyright (C) 2012 Chiyuan Zhang
 */

#include <set>
#include <map>
#include <vector>
#include <algorithm>

#include <shogun/evaluation/ClusteringEvaluation.h>
#include <shogun/labels/MulticlassLabels.h>
#include <shogun/mathematics/munkres.h>

using namespace shogun;
using namespace std;

int32_t CClusteringEvaluation::find_match_count(SGVector<int32_t> l1, int32_t m1, SGVector<int32_t> l2, int32_t m2)
{
    int32_t match_count=0;
    for (int32_t i=l1.vlen-1; i >= 0; --i)
    {
        if (l1[i] == m1 && l2[i] == m2)
            match_count++;
    }

    return match_count;
}

int32_t CClusteringEvaluation::find_mismatch_count(SGVector<int32_t> l1, int32_t m1, SGVector<int32_t> l2, int32_t m2)
{
    return l1.vlen - find_match_count(l1, m1, l2, m2);
}

void CClusteringEvaluation::best_map(CLabels* predicted, CLabels* ground_truth)
{
    ASSERT(predicted->get_num_labels() == ground_truth->get_num_labels());
    ASSERT(predicted->get_label_type() == LT_MULTICLASS);
    ASSERT(ground_truth->get_label_type() == LT_MULTICLASS);

    SGVector<float64_t> label_p=((CMulticlassLabels*) predicted)->get_unique_labels();
    SGVector<float64_t> label_g=((CMulticlassLabels*) ground_truth)->get_unique_labels();

    SGVector<int32_t> predicted_ilabels=((CMulticlassLabels*) predicted)->get_int_labels();
    SGVector<int32_t> groundtruth_ilabels=((CMulticlassLabels*) ground_truth)->get_int_labels();

    int32_t n_class=max(label_p.vlen, label_g.vlen);
    SGMatrix<float64_t> G(n_class, n_class);
    G.zero();

    for (int32_t i=0; i < label_g.vlen; ++i)
    {
        for (int32_t j=0; j < label_p.vlen; ++j)
        {
            G(i, j)=find_mismatch_count(groundtruth_ilabels, static_cast<int32_t>(label_g[i]),
                predicted_ilabels, static_cast<int32_t>(label_p[j]));
        }
    }

    Munkres munkres_solver(G);
    munkres_solver.solve();

    std::map<int32_t, int32_t> label_map;
    for (int32_t i=0; i < label_p.vlen; ++i)
    {
        for (int32_t j=0; j < label_g.vlen; ++j)
        {
            if (G(j, i) == 0)
            {
                label_map.insert(make_pair(static_cast<int32_t>(label_p[i]), 
                        static_cast<int32_t>(label_g[j])));
                break;
            }
        }
    }

    for (int32_t i= 0; i < predicted_ilabels.vlen; ++i)
        ((CMulticlassLabels*) predicted)->set_int_label(i, label_map[predicted_ilabels[i]]);
}