vcglib/vcg/math/histogram.h

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/****************************************************************************
* VCGLib o o *
* Visual and Computer Graphics Library o o *
* _ O _ *
* Copyright(C) 2004 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* 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 (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
/****************************************************************************
History
$Log: not supported by cvs2svn $
2008-03-06 11:45:39 +01:00
Revision 1.18 2008/03/05 11:21:49 cignoni
Heavily refactored the whole structure.
Some interfaces have been changed. Be careful.
Revision 1.17 2008/02/29 12:15:06 cignoni
added maxcount
2008-02-29 13:15:06 +01:00
Revision 1.16 2006/11/28 21:29:21 cignoni
Re added typedef Histogramf and Histogramd
Revision 1.15 2006/11/28 09:47:42 corsini
add documentation
fix typo
2006-11-28 10:47:42 +01:00
Revision 1.14 2006/05/04 00:09:53 cignoni
minor change: removed unused vars
2006-05-04 02:09:53 +02:00
Revision 1.13 2006/03/29 09:25:47 zifnab1974
extra includes necessary for compilation of meshlab on AMD 64 with gcc 3.4.5
Revision 1.12 2006/01/12 13:12:54 callieri
in FileWrite, added file closing after finishing
Revision 1.11 2005/09/16 11:51:23 cignoni
removed signed/unsigned warning
2005-09-16 13:51:23 +02:00
Revision 1.10 2005/06/17 00:54:55 cignoni
Corrected small bug in SetRange (H was resized to n instead of n+1)
Revision 1.9 2005/06/14 14:27:00 ganovelli
added include of algorithm
2005-06-14 16:27:00 +02:00
Revision 1.8 2005/06/10 14:59:39 cignoni
Added include assert.h and cast to ScalarType for a pow in SetRange() function.
Revision 1.7 2005/06/09 14:19:55 cignoni
Added typedef Histogramf and Histogramd
Revision 1.6 2005/06/07 09:37:33 ponchio
Added fabs() to variance, which can sometime be negative in case
of rounding errors (and sqrt chokes on it).
Revision 1.5 2005/06/07 07:44:08 cignoni
Added Percentile and removed small bug in Add
Revision 1.4 2005/04/04 10:48:35 cignoni
Added missing functions Avg, rms etc, now fully (almost) functional
Revision 1.3 2005/03/14 09:23:40 cignoni
Added missing include<vector>
2005-03-14 10:23:40 +01:00
Revision 1.2 2004/08/25 15:15:26 ganovelli
minor changes to comply gcc compiler (typename's and stuff)
Revision 1.1 2004/06/24 09:12:28 cignoni
Initial Release
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****************************************************************************/
#ifndef __VCG_HISTOGRAM
#define __VCG_HISTOGRAM
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#include <vector>
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#include <algorithm>
#include <assert.h>
#include <string>
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#include <limits>
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namespace vcg {
/**
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* Histogram.
*
* This class implements a single-value histogram.
*/
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template <class ScalarType>
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class Histogram
{
// public data members
private:
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std::vector <int> H; //! Counters for bins.
std::vector <ScalarType> R; //! Range for bins.
ScalarType minv; //! Minimum value.
ScalarType maxv; //! Maximum value.
int n; //! Number of vaild intervals stored between minv and maxv.
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/// incrementally updated values
int cnt; //! Number of accumulated samples.
ScalarType avg; //! Average.
ScalarType rms; //! Root mean square.
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/**
* Returns the index of the bin which contains a given value.
*/
int BinIndex(ScalarType val) ;
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// public methods
public:
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/**
* Set the histogram values.
*
* This method is used to correctly initialize the bins of the histogram.
* n is the number of valid intervals between minv and maxv.
* for a more robust working, the Histogram class stores also the two out of range intervals (-inf, minv] and [maxv, +inf)
* Each bin is left closed (eg it contains the value
* The \a gamma parameter is applied to modify the distribution of the ranges of the bins. Default uniform distibution.
*
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*/
void SetRange(ScalarType _minv, ScalarType _maxv, int _n,ScalarType gamma=1.0 );
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ScalarType MinV() {return minv;}; //! Minimum value.
ScalarType MaxV() {return maxv;}; //! Minimum value.
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/**
* Add a new value to the histogram.
*
* The statistics related to the histogram data (average, RMS, etc.) are
* also updated.
*/
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void Add(ScalarType v);
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int MaxCount() const;
int BinCount(ScalarType v);
int BinCount(ScalarType v, ScalarType width);
int RangeCount(ScalarType rangeMin, ScalarType rangeMax);
ScalarType BinWidth(ScalarType v);
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/**
* Returns the value corresponding to a given percentile of the data.
*
* The percentile range between 0 and 1.
*/
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ScalarType Percentile(ScalarType frac) const;
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//! Returns the average of the data.
ScalarType Avg(){ return avg/cnt;}
//! Returns the Root Mean Square of the data.
ScalarType RMS(){ return sqrt(rms/double(cnt));}
//! Returns the variance of the data.
ScalarType Variance(){ return fabs(rms/cnt-Avg()*Avg());}
//! Returns the standard deviation of the data.
ScalarType StandardDeviation(){ return sqrt(Variance());}
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//! Dump the histogram to a file.
void FileWrite(const std::string &filename);
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//! Reset histogram data.
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void Clear();
};
template <class ScalarType>
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void Histogram<ScalarType>::Clear()
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{
H.clear();
R.clear();
cnt=0;
avg=0;
rms=0;
n=0;
minv=0;
maxv=1;
}
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/*
Note that the histogram holds <n> valid bins plus two semi-infinite bins.
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R[0] = -inf
R[1] = minv
R[n+1] = maxv
R[n+2] = +inf
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Eg. SetRange(0, 10, 5) asks for 5 intervals covering the 0..10 range
H[0] H[1] H[2] H[3] H[4] H[5] H[6]
-inf 0 2 4 6 8 10 +inf
R[0] R[1] R[2] R[3] R[4] R[5] R[6] R[7]
*/
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template <class ScalarType>
void Histogram<ScalarType>::SetRange(ScalarType _minv, ScalarType _maxv, int _n, ScalarType gamma)
{
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// reset data
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Clear();
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minv=_minv;maxv=_maxv;n=_n;
H.resize(n+2);
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fill(H.begin(),H.end(),0);
R.resize(n+3);
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R[0] = - std::numeric_limits< ScalarType >::max();
R[n+2] = std::numeric_limits< ScalarType >::max();
double delta=(maxv-minv);
if(gamma==1)
{
for(int i=0; i<=n; ++i)
R[i+1] = minv + delta*ScalarType(i)/n;
}
else
{
for(int i=0; i<=n; ++i)
R[i+1] = minv + delta*pow(ScalarType(i)/n,gamma);
}
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}
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template <class ScalarType>
int Histogram<ScalarType>::BinIndex(ScalarType val)
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{
// lower_bound returns the furthermost iterator i in [first, last) such that, for every iterator j in [first, i), *j < value.
// E.g. An iterator pointing to the first element "not less than" val, or end() if every element is less than val.
typename std::vector<ScalarType>::iterator it = lower_bound(R.begin(),R.end(),val);
assert(it!=R.begin());
assert(it!=R.end());
assert((*it)>=val);
int pos = it-R.begin();
assert(pos >=1);
pos -= 1;
assert (R[pos] < val);
assert ( val <= R[pos+1] );
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return pos;
}
/*
H[0] H[1] H[2] H[3] H[4] H[5] H[6]
-inf 0 2 4 6 8 10 +inf
R[0] R[1] R[2] R[3] R[4] R[5] R[6] R[7]
asking for 3.14 lower bound will return an iterator pointing to R[3]==4; and will increase H[2]
asking for 4 lower bound will return an iterator pointing to R[3]==4; and will increase H[2]
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*/
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template <class ScalarType>
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void Histogram<ScalarType>::Add(ScalarType v)
{
int pos=BinIndex(v);
if(pos>=0 && pos<=n)
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{
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++H[pos];
++cnt;
avg+=v;
rms += v*v;
}
}
template <class ScalarType>
int Histogram<ScalarType>::BinCount(ScalarType v)
{
return H[BinIndex(v)];
}
template <class ScalarType>
int Histogram<ScalarType>::BinCount(ScalarType v, ScalarType width)
{
return RangeCount(v-width/2.0,v+width/2.0);
}
template <class ScalarType>
int Histogram<ScalarType>::RangeCount(ScalarType rangeMin, ScalarType rangeMax)
{
int firstBin=BinIndex(rangeMin);
int lastBin=BinIndex (rangeMax);
int sum=0;
for(int i=firstBin; i<=lastBin;++i)
sum+=H[i];
return sum;
}
template <class ScalarType>
ScalarType Histogram<ScalarType>::BinWidth(ScalarType v)
{
int pos=BinIndex(v);
return R[pos+1]-R[pos];
}
template <class ScalarType>
void Histogram<ScalarType>::FileWrite(const std::string &filename)
{
FILE *fp;
fp=fopen(filename.c_str(),"w");
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for(unsigned int i=0; i<H.size(); i++)
fprintf (fp,"%12.8lf , %12.8lf \n",R[i],double(H[i])/cnt);
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fclose(fp);
}
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template <class ScalarType>
int Histogram<ScalarType>::MaxCount() const
{
return *(std::max_element(H.begin(),H.end()));
}
// Return the scalar value <r> such that there are <frac> samples <= <r>.
// E.g. Percentile(0.0) will return R[1] e.g. min value
// E.g. Percentile(1.0) will return R[n+1] e.g max value
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template <class ScalarType>
ScalarType Histogram<ScalarType>::Percentile(ScalarType frac) const
{
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if(H.size()==0 && R.size()==0)
return 0;
// check percentile range
assert(frac >= 0 && frac <= 1);
ScalarType sum=0,partsum=0;
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int i;
// useless summation just to be sure
for(i=0;i<H.size();i++) sum+=H[i];
assert(sum==cnt);
sum*=frac;
for(i=0; i<H.size(); i++)
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{
partsum+=H[i];
if(partsum>=sum) break;
}
assert(i<H.size());
return R[i+1];
}
typedef Histogram<double> Histogramd ;
typedef Histogram<float> Histogramf ;
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} // end namespace (vcg)
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#endif /* __VCG_HISTOGRAM */