WinsorizedSigmaClippingRejection.h

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//     ____   ______ __
//    / __ \ / ____// /
//   / /_/ // /    / /
//  / ____// /___ / /___   PixInsight Class Library
// /_/     \____//_____/   PCL 2.7.0
// ----------------------------------------------------------------------------
// pcl/WinsorizedSigmaClippingRejection.h - Released 2024-06-18T15:48:54Z
// ----------------------------------------------------------------------------
// This file is part of the PixInsight Class Library (PCL).
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// ----------------------------------------------------------------------------
 
#ifndef __PCL_WinsorizedSigmaClippingRejection_h
#define __PCL_WinsorizedSigmaClippingRejection_h
 
 
#include <pcl/Defs.h>
#include <pcl/Diagnostics.h>
 
#include <pcl/Array.h>
#include <pcl/Math.h>
 
namespace pcl
{
 
// ----------------------------------------------------------------------------
 
class PCL_CLASS WinsorizedSigmaClippingRejection
{
public:
 
   WinsorizedSigmaClippingRejection() = default;
 
   WinsorizedSigmaClippingRejection( const WinsorizedSigmaClippingRejection& ) = default;
 
   virtual ~WinsorizedSigmaClippingRejection()
   {
   }
 
   WinsorizedSigmaClippingRejection& operator =( const WinsorizedSigmaClippingRejection& ) = default;
 
   bool ClipLow() const
   {
      return m_clipLow;
   }
 
   bool ClipHigh() const
   {
      return m_clipHigh;
   }
 
   void EnableLowClipping( bool enable = true )
   {
      m_clipLow = enable;
   }
 
   void DisableLowClipping( bool disable = true )
   {
      EnableLowClipping( !disable );
   }
 
   void EnableHighClipping( bool enable = true )
   {
      m_clipHigh = enable;
   }
 
   void DisableHighClipping( bool disable = true )
   {
      EnableHighClipping( !disable );
   }
 
   float LowSigma() const
   {
      return m_sigmaLow;
   }
 
   float HighSigma() const
   {
      return m_sigmaHigh;
   }
 
   void SetLowSigma( float sigma )
   {
      PCL_PRECONDITION( sigma >= 0 )
      m_sigmaLow = Max( 0.0F, sigma );
   }
 
   void SetHighSigma( float sigma )
   {
      PCL_PRECONDITION( sigma >= 0 )
      m_sigmaHigh = Max( 0.0F, sigma );
   }
 
   float WinsorizationCutoff() const
   {
      return m_cutoff;
   }
 
   void SetWinsorizationCutoff( float cutoff )
   {
      PCL_PRECONDITION( cutoff >= 1 )
      m_cutoff = Max( 1.0F, cutoff );
   }
 
   template <class C, typename I>
   void PerformRejection( I& i, I& j, double& mean, double& sigma, C& data ) const
   {
      data.Sort();
      i = I( 0 );
      j = I( data.Length() );
      for ( int it = 0; ; ++it )
      {
         GetWinsorizedParameters( mean, sigma, i, j, data, (it > 0) ? .0F : m_cutoff );
         if ( 1 + sigma == 1 )
            return;
         if ( I( j - i ) < I( 3 ) )
            return;
 
         int c = 0;
         if ( m_clipLow )
            for ( ; i < j; ++i, ++c )
               if ( (mean - data[i])/sigma <= m_sigmaLow )
                  break;
         if ( m_clipHigh )
            for ( ; i < j; --j, ++c )
               if ( (data[j-1] - mean)/sigma <= m_sigmaHigh )
                  break;
         if ( c == 0 )
            return;
      }
   }
 
   template <class C, typename I>
   void operator()( I& i, I& j, double& mean, double& sigma, C& data ) const
   {
      return PerformRejection( i, j, mean, sigma, data );
   }
 
private:
 
   bool  m_clipLow = true;  // perform rejection of low values
   bool  m_clipHigh = true; // perform rejection of high values
   float m_sigmaLow = 3;    // rejection sigma, low values
   float m_sigmaHigh = 3;   // rejection sigma, high values
   float m_cutoff = 5;      // Winsorization cutoff point in sigma units
 
   template <class C, typename I>
   static void GetWinsorizedParameters( double& mean, double& sigma, const I i, const I j, const C& data, float cutoff )
   {
      size_type n = size_type( j - i );
      if ( n < 2 )
      {
         mean = sigma = 0;
         return;
      }
 
      Array<double> v( n );
      {
         size_type l = 0;
         for ( I k = i; k < j; ++k, ++l )
            v[l] = double( data[k] );
      }
 
      mean = MedianDestructive( v.Begin(), v.End() );
      sigma = 1.1926*Sn( v.Begin(), v.End() );
      v.Sort();
 
      for ( int it = 0;; )
      {
         if ( 1 + sigma == 1 )
            break;
 
         double t0 = mean - 1.5*sigma;
         double t1 = mean + 1.5*sigma;
 
         if ( cutoff > 0 )
         {
            double c0 = mean - cutoff*sigma;
            double c1 = mean + cutoff*sigma;
            for ( size_type i = 0; i < n; ++i )
               if ( v[i] < t0 )
                  v[i] = (v[i] > c0) ? t0 : mean;
               else if ( v[i] > t1 )
                  v[i] = (v[i] < c1) ? t1 : mean;
         }
         else
         {
            for ( size_type i = 0; i < n; ++i )
               if ( v[i] < t0 )
                  v[i] = t0;
               else if ( v[i] > t1 )
                  v[i] = t1;
         }
 
         double s0 = sigma;
         sigma = 1.134*StdDev( v.Begin(), v.End() );
         mean = Mean( v.Begin(), v.End() );
         if ( ++it > 1 )
            if ( Abs( s0 - sigma )/s0 < 0.0005 )
               break;
      }
   }
};
 
// ----------------------------------------------------------------------------
 
} // pcl
 
#endif   // __PCL_WinsorizedSigmaClippingRejection_h
 
// ----------------------------------------------------------------------------
// EOF pcl/WinsorizedSigmaClippingRejection.h - Released 2024-06-18T15:48:54Z