FastLowessSmoothing.h

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// $Maintainer: Hannes Roest $
// $Authors: Hannes Roest $
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#pragma once

#include <OpenMS/CONCEPT/Macros.h>
#include <vector>
#include <algorithm>    // std::min, std::max
#include <functional>

namespace OpenMS
{

  namespace FastLowessSmoothing
  {

    int OPENMS_DLLAPI lowess(const std::vector<double>& x, const std::vector<double>& y,
               double f, int nsteps, double delta, std::vector<double>& result);

    inline int OPENMS_DLLAPI lowess(const std::vector<double>& x, const std::vector<double>& y,
               std::vector<double>& result)
    {
      OPENMS_PRECONDITION(x.size() == y.size(), "Vectors x and y must have the same length")
      OPENMS_PRECONDITION(x.size() >= 2, "Need at least two points for smoothing")
      OPENMS_PRECONDITION(std::adjacent_find(x.begin(), x.end(), std::greater<double>()) == x.end(),
          "The vector x needs to be sorted")

      double delta = 0.01 * (x[ x.size()-1 ] - x[0]); // x is sorted
      return lowess(x, y, 2.0/3, 3, delta, result);
    }
  }

} // namespace OpenMS