view src/DistanceMetric.cpp @ 156:d6df9fe7b12f refactors

Implement distance metric selection (euclidean or cosine)

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Vamp feature extraction plugin using the MATCH audio alignment
    algorithm.

    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2007 Simon Dixon, Chris Cannam and QMUL.
    
    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 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#include "DistanceMetric.h"

#include <cassert>
#include <cmath>
#include <iostream>

using namespace std;

//#define DEBUG_DISTANCE_METRIC 1

DistanceMetric::DistanceMetric(Parameters params) :
    m_params(params)
{
#ifdef DEBUG_DISTANCE_METRIC
    cerr << "*** DistanceMetric: norm = " << m_params.norm
         << endl;
#endif
}

double
DistanceMetric::calcDistance(const vector<double> &f1,
			     const vector<double> &f2)
{
    double d = 0;
    double sum = 0;
    double eps = 1e-16;

    int featureSize = f1.size();
    assert(int(f2.size()) == featureSize);

    if (m_params.metric == Cosine) {

        double num = 0, denom1 = 0, denom2 = 0;
        
        for (int i = 0; i < featureSize; ++i) {
            num += f1[i] * f2[i];
            denom1 += f1[i] * f1[i];
            denom2 += f2[i] * f2[i];
        }

        d = 1.0 - (num / (eps + sqrt(denom1 * denom2)));

        if (m_params.noise == AddNoise) {
            d += 1e-2;
        }
        if (d > 1.0) d = 1.0;
        
        return d; // normalisation param ignored
    }

    // Euclidean
    
    for (int i = 0; i < featureSize; i++) {
        d += fabs(f1[i] - f2[i]);
        sum += fabs(f1[i]) + fabs(f2[i]);
    }

    double noise = 1e-3 * featureSize;
    if (m_params.noise == AddNoise) {
        d += noise;
        sum += noise;
    }
    
    if (sum == 0) {
        return 0;
    }

    double distance = 0;

    if (m_params.norm == NormaliseDistanceToSum) {

        distance = d / sum; // 0 <= d/sum <= 2

    } else if (m_params.norm == NormaliseDistanceToLogSum) {

        // note if this were to be restored, it would have to use
        // totalEnergies vector instead of f1[freqMapSize] which used to
        // store the total energy:
        //	double weight = (5 + Math.log(f1[freqMapSize] + f2[freqMapSize]))/10.0;

        double weight = (8 + log(sum)) / 10.0;
    
        if (weight < 0) weight = 0;
        else if (weight > 1) weight = 1;

        distance = d / sum * weight;

    } else {

        distance = d;
    }
    
    return distance;
}