MulticlassAccuracy.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) 2011 Sergey Lisitsyn
 * Copyright (C) 2011 Berlin Institute of Technology and Max-Planck-Society
 */

#include <shogun/evaluation/MulticlassAccuracy.h>
#include <shogun/labels/Labels.h>
#include <shogun/labels/MulticlassLabels.h>
#include <shogun/mathematics/Math.h>

using namespace shogun;

float64_t CMulticlassAccuracy::evaluate(CLabels* predicted, CLabels* ground_truth)
{
    ASSERT(predicted && 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)
    int32_t length = predicted->get_num_labels();
    int32_t correct = 0;
    if (m_ignore_rejects)
    {
        for (int32_t i=0; i<length; i++)
        {
            if (((CMulticlassLabels*) predicted)->get_int_label(i)==((CMulticlassLabels*) ground_truth)->get_int_label(i))
                correct++;
        }
        return ((float64_t)correct)/length;
    }
    else
    {
        int32_t total = length;
        for (int32_t i=0; i<length; i++)
        {
            int32_t predicted_label = ((CMulticlassLabels*) predicted)->get_int_label(i);

            if (predicted_label==((CMulticlassLabels*) predicted)->REJECTION_LABEL)
                total--;
            else if (predicted_label==((CMulticlassLabels*) ground_truth)->get_int_label(i))
                correct++;
        }
        m_rejects_num = length-total;
        SG_DEBUG("correct=%d, total=%d, rejected=%d\n",correct,total,length-total)
        return ((float64_t)correct)/total;
    }
    return 0.0;
}

SGMatrix<int32_t> CMulticlassAccuracy::get_confusion_matrix(CLabels* predicted, CLabels* ground_truth)
{
    ASSERT(predicted->get_num_labels() == ground_truth->get_num_labels())
    int32_t length = ground_truth->get_num_labels();
    int32_t num_classes = ((CMulticlassLabels*) ground_truth)->get_num_classes();
    SGMatrix<int32_t> confusion_matrix(num_classes, num_classes);
    memset(confusion_matrix.matrix,0,sizeof(int32_t)*num_classes*num_classes);
    for (int32_t i=0; i<length; i++)
    {
        int32_t predicted_label = ((CMulticlassLabels*) predicted)->get_int_label(i);
        int32_t ground_truth_label = ((CMulticlassLabels*) ground_truth)->get_int_label(i);

        if (predicted_label==((CMulticlassLabels*) predicted)->REJECTION_LABEL)
            continue;

        confusion_matrix[predicted_label*num_classes+ground_truth_label]++;
    }
    return confusion_matrix;
}