BSplineSmoothingSpline.h

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// --------------------------------------------------------------------------
//                   OpenMS -- Open-Source Mass Spectrometry
// --------------------------------------------------------------------------
// SPDX-License-Identifier: BSD-3-Clause
//
// --------------------------------------------------------------------------
// $Maintainer: Justin Sing $
// $Authors: Justin Sing $
// --------------------------------------------------------------------------
 
#pragma once
 
#include <OpenMS/config.h>
#include <OpenMS/MATH/MISC/BSpline2d.h>
#include <vector>
#include <memory>
 
namespace OpenMS
{
  namespace Math
  {
    class OPENMS_DLLAPI BSplineSmoothingSpline
    {
    public:
      BSplineSmoothingSpline(const std::vector<double>& x,
                             const std::vector<double>& y,
                             double s = -1.0,
                             int k = 3);
 
      ~BSplineSmoothingSpline();
 
      BSplineSmoothingSpline(const BSplineSmoothingSpline&) = delete;
 
      BSplineSmoothingSpline& operator=(const BSplineSmoothingSpline&) = delete;
 
      BSplineSmoothingSpline(BSplineSmoothingSpline&&) = default;
 
      BSplineSmoothingSpline& operator=(BSplineSmoothingSpline&&) = default;
 
      double eval(double x) const;
 
      bool ok() const { return ok_; }
 
      int num_interior_knots() const { return num_interior_knots_; }
 
      double rss() const { return rss_; }
 
      double smoothing_param() const { return s_; }
 
    private:
      bool ok_ = false;
      int num_interior_knots_ = 0;
      double rss_ = 0.0;
      double s_ = 0.0;
      int k_ = 3;
      std::vector<double> x_;
      std::vector<double> y_;
      
      // Fit type
      enum FitType { POLYNOMIAL, BSPLINE };
      FitType fit_type_ = BSPLINE;
      
      // Polynomial coefficients [a0, a1, a2, a3] for a0 + a1*x + a2*x^2 + a3*x^3
      std::vector<double> poly_coeffs_;
      
      // The fitted BSpline (owned, only used if fit_type_ == BSPLINE)
      std::unique_ptr<BSpline2d> spline_;
 
      void fit_smoothing_spline(const std::vector<double>& x,
                                const std::vector<double>& y,
                                double s_target);
 
      bool try_polynomial_fit(const std::vector<double>& x,
                              const std::vector<double>& y,
                              double s_target,
                              int degree = 3);
 
      double compute_rss(const BSpline2d* spl,
                        const std::vector<double>& x,
                        const std::vector<double>& y) const;
      
      double compute_polynomial_rss(const std::vector<double>& x,
                                    const std::vector<double>& y) const;
      
      double eval_polynomial(double x) const;
    };
 
  } // namespace Math
} // namespace OpenMS