/usr/include/CLAM/CircularPeakPicking.hxx is in libclam-dev 1.4.0-7.
This file is owned by root:root, with mode 0o644.
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* Copyright (c) 2001-2006 MUSIC TECHNOLOGY GROUP (MTG)
* UNIVERSITAT POMPEU FABRA
*
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#ifndef CircularPeakPicking_hxx
#define CircularPeakPicking_hxx
#include <list>
#include <vector>
namespace Simac
{
/**
* This processing takes a vector of scalars magnitudes and returns
* a list of peaks found considering that the first and last bins
* are neighbors.
* Peaks are detected when there is a bin that is greater that neighbor
* at both sides.
* Then peak position and value are interpolated using a quadratic function
* that passes also by the two neighbors bins.
*
* The first bin is considered at offset and each bin increases binSize.
* By default, binSize and offset are 1 and 0 so that the bin position
* matches the resulting position.
*
* @author David Garcia
*/
class CircularPeakPicking
{
public:
typedef std::vector<std::pair<double, double> > PeakList;
private:
PeakList _output;
unsigned int _maxSize;
double _binSize;
double _offset;
public:
CircularPeakPicking(unsigned chromagramSize, double binSize=1.0, double offset=0.0)
: _maxSize(chromagramSize), _binSize(binSize), _offset(offset)
{
_output.reserve(chromagramSize);
}
/**
* Find the maximum of an interpolated quadratic polynomial function
* giving the samples at three equidistant points at x=0, x=1 and x=2.
* You can use it for any equidistant samples just by adding x0 to
* the resulting xmax.
*
* @pre The function will fail when y0>=y1 or y2>=y1, as it is supposed to
* be applied after having located a peak in y1.
* @returns A pair containing xmax,ymax
*/
std::pair<double,double> interpolate(double y0, double y1, double y2)
{
// From the quadratic lagrange interpolation
// y= y0(x1-x)(x2-x)/(x1-x0)(x2-x0) +
// + y1(x-x0)(x2-x)/(x1-x0)(x2-x0) +
// + y1(x2-x)(x-x0)/(x2-x1)(x2-x0) +
// + y2(x-x1)(x-x0)/(x2-x1)(x2-x0) =
//
// considering x0=0, x1=1 and x2=2
//
// = y0(x-1)(x-2)/2 +
// - y1(x)(x-2)/2 +
// - y1(x-2)(x)/2 +
// + y2(x-1)(x)/2 =
//
// = y0(x-1)(x-2)/2 +
// - y1(x-2)(x) +
// + y2(x-1)(x)/2 =
//
// = y0/2 (x^2 - 3x + 2) - y1 (x^2-2x) + y2/2 (x^2-x)
// = (y0/2-y1+y2/2) x^2 + (-3*y0/2 + 2*y1 - y2/2) x + y0
double a = y0/2 - y1 + y2/2;
double b = y1 -y0 -a; // = -3*y0/2 + 2*y1 -y2/2;
double c = y0;
// From equating to zero the derivate of x*x*a + x*b + c
double xmax = -b/(a*2);
// ymax = xmax*xmax*a + b*xmax + c =
// = a*b*b/(4*a*a) -b*b/(2*a) + c =
// = b*b/(4*a) -b*b/(2*a) + c =
// = -b*b/(4*a) + c
double ymax = b*xmax/2 + y0;
return std::make_pair(xmax, ymax);
}
void doIt(const std::vector<double> & chromagram)
{
_output.resize(0);
unsigned i0=_maxSize-2;
unsigned i1=_maxSize-1;
for (unsigned i=0; i<_maxSize; i0=i1, i1=i, i++)
{
// not equal to support plain two bins peaks
if (chromagram[i0] > chromagram[i1]) continue;
if (chromagram[i ] >= chromagram[i1]) continue;
std::pair<double,double> interpoled=
interpolate(chromagram[i0],chromagram[i1],chromagram[i]);
// Adding the base bin
interpoled.first+=i0;
// Folding to [0,_maxSize) interval
while (interpoled.first<0) interpoled.first +=_maxSize;
while (interpoled.first>=_maxSize) interpoled.first -=_maxSize;
// Scaling
interpoled.first*=_binSize;
// Shifting to the first bin position
interpoled.first+=_offset;
_output.push_back(interpoled);
}
}
const PeakList & output() const
{
return _output;
}
};
} // namespace Simac
#endif// CircularPeakPicking_hxx
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