Rescale is a math code snippet to rescale a double, 1D std::vector or 2D std::vector from a certain range to a new range.

Rescale on a double


#include <algorithm>

#include <cassert>



//From http://www.richelbilderbeek.nl/CppRescale.htm

const double Rescale(

  const double value,

  const double oldMin,

  const double oldMax,

  const double newMin,

  const double newMax)

{

  assert(value >= oldMin);

  assert(value <= oldMax);

  const double oldDistance = oldMax - oldMin;

  //At which relative distance is value on oldMin to oldMax ?

  const double distance = (value - oldMin) / oldDistance;

  assert(distance >= 0.0);

  assert(distance <= 1.0);

  const double newDistance = newMax - newMin;

  const double newValue = newMin + (distance * newDistance);

  assert(newValue >= newMin);

  assert(newValue <= newMax);

  return newValue;

}

Rescale on a 1D std::vector


#include <algorithm>

#include <cassert>

#include <vector>



//From http://www.richelbilderbeek.nl/CppRescale.htm

const std::vector<double> Rescale(

  std::vector<double> v,

  const double newMin,

  const double newMax)

{

  const double oldMin = *std::min_element(v.begin(),v.end());

  const double oldMax = *std::max_element(v.begin(),v.end());

  typedef std::vector<double>::iterator Iter;

  Iter i = v.begin();

  const Iter j = v.end();

  for ( ; i!=j; ++i)

  {

    *i = Rescale(*i,oldMin,oldMax,newMin,newMax);

  }

  return v;

}

Rescale on a 2D std::vector


#include <algorithm>

#include <cassert>

#include <vector>



//From http://www.richelbilderbeek.nl/CppRescale.htm

const std::vector<std::vector<double> > Rescale(

  std::vector<std::vector<double> > v,

  const double newMin,

  const double newMax)

{

  const double oldMin = MinElement(v);

  const double oldMax = MaxElement(v);

  typedef std::vector<std::vector<double> >::iterator RowIter;

  RowIter y = v.begin();

  const RowIter maxy = v.end();

  for ( ; y!=maxy; ++y)

  {

    typedef std::vector<double>::iterator ColIter;

    ColIter x = y->begin();

    const ColIter maxx = y->end();

    for ( ; x!=maxx; ++x)

    {

      *x = Rescale(*x,oldMin,oldMax,newMin,newMax);

    }

  }

  return v;

}

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

This page has been created by the tool CodeToHtml

(C++) Rescale

Rescale on a double

Rescale on a 1D std::vector

Rescale on a 2D std::vector