itkImageRandomNonRepeatingConstIteratorWithIndex.h

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 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkImageRandomNonRepeatingConstIteratorWithIndex_h
#define itkImageRandomNonRepeatingConstIteratorWithIndex_h
 
#include "itkImageConstIteratorWithIndex.h"
#include <algorithm>
#include <iostream>
#include <type_traits> // For remove_const_t.
#include "itkMersenneTwisterRandomVariateGenerator.h"
 
namespace itk
{
class NodeOfPermutation
{
public:
  SizeValueType m_Priority{ 0 };
  SizeValueType m_Index{ 0 };
  double        m_Value{ 0.0 };
 
  NodeOfPermutation() = default;
 
  bool
  operator<(const NodeOfPermutation & b) const
  {
    if (m_Priority == b.m_Priority)
    {
      return m_Value < b.m_Value;
    }
 
    return m_Priority < b.m_Priority;
  }
};

class RandomPermutation
{
public:
  using GeneratorPointer = Statistics::MersenneTwisterRandomVariateGenerator::Pointer;
  NodeOfPermutation * m_Permutation;
  GeneratorPointer    m_Generator;
  SizeValueType       m_Size;
 
  RandomPermutation(SizeValueType sz)
    : m_Size(sz)
  {
    m_Permutation = new NodeOfPermutation[m_Size];
    m_Generator = Statistics::MersenneTwisterRandomVariateGenerator::New();
    this->Shuffle();
  }
 
  RandomPermutation &
  operator=(const RandomPermutation & it)
  {
    delete[] m_Permutation;
    m_Size = it.m_Size;
    m_Permutation = new NodeOfPermutation[m_Size];
    m_Generator = it.m_Generator;
    return *this;
  }
 
  void
  SetPriority(SizeValueType i, SizeValueType priority) const
  {
    if (i > m_Size)
    {
      std::ostringstream ostrm;
      ostrm << "Error: RandomPermuation does not have " << i << " elements" << std::endl;
      throw std::runtime_error(ostrm.str());
    }
 
    m_Permutation[i].m_Priority = priority;
  }
 
  void
  Shuffle() const
  {
    for (SizeValueType i = 0; i < m_Size; ++i)
    {
      m_Permutation[i].m_Value = m_Generator->GetVariateWithClosedRange(1.0);
      m_Permutation[i].m_Index = i;
    }
    std::sort(m_Permutation, m_Permutation + m_Size);
  }
 
  SizeValueType
  operator[](SizeValueType i) const
  {
    return m_Permutation[i].m_Index;
  }
 
  ~RandomPermutation() { delete[] m_Permutation; }

  void
  ReinitializeSeed() const
  {
    m_Generator->SetSeed();
  }
 
  void
  ReinitializeSeed(unsigned int seed) const
  {
    m_Generator->SetSeed(seed);
  }
};

template <typename TImage>
class ITK_TEMPLATE_EXPORT ImageRandomNonRepeatingConstIteratorWithIndex : public ImageConstIteratorWithIndex<TImage>
{
public:
  using Self = ImageRandomNonRepeatingConstIteratorWithIndex;
  using Superclass = ImageConstIteratorWithIndex<TImage>;

  using typename Superclass::IndexType;
  using typename Superclass::SizeType;
  using typename Superclass::OffsetType;
  using typename Superclass::RegionType;
  using typename Superclass::ImageType;
  using typename Superclass::PixelContainer;
  using typename Superclass::PixelContainerPointer;
  using typename Superclass::InternalPixelType;
  using typename Superclass::PixelType;
  using typename Superclass::AccessorType;
  using typename Superclass::IndexValueType;
  using typename Superclass::OffsetValueType;
  using typename Superclass::SizeValueType;

  ImageRandomNonRepeatingConstIteratorWithIndex() = default;
 
  ~ImageRandomNonRepeatingConstIteratorWithIndex() override { delete m_Permutation; }

  ImageRandomNonRepeatingConstIteratorWithIndex(const TImage * ptr, const RegionType & region);

  ImageRandomNonRepeatingConstIteratorWithIndex(const ImageConstIteratorWithIndex<TImage> & it)
 
  {
    this->ImageConstIteratorWithIndex<TImage>::operator=(it);
  }

  Self &
  operator=(const Self & it);

  void
  GoToBegin()
  {
    m_NumberOfSamplesDone = 0L;
    this->UpdatePosition();
  }

  void
  GoToEnd()
  {
    m_NumberOfSamplesDone = m_NumberOfSamplesRequested;
    this->UpdatePosition();
  }

  [[nodiscard]] bool
  IsAtBegin() const
  {
    return m_NumberOfSamplesDone == 0L;
  }

  [[nodiscard]] bool
  IsAtEnd() const
  {
    return m_NumberOfSamplesDone >= m_NumberOfSamplesRequested;
  }

  static constexpr unsigned int ImageDimension = TImage::ImageDimension;

  using PriorityImageType = itk::Image<SizeValueType, Self::ImageDimension>;

  void
  SetPriorityImage(const PriorityImageType * priorityImage);

  Self &
  operator++()
  {
    ++m_NumberOfSamplesDone;
    this->UpdatePosition();
    return *this;
  }

  Self &
  operator--()
  {
    --m_NumberOfSamplesDone;
    this->UpdatePosition();
    return *this;
  }

  void
  SetNumberOfSamples(SizeValueType number)
  {
    m_NumberOfSamplesRequested = number;
    if (number > m_NumberOfPixelsInRegion)
    {
      m_NumberOfSamplesRequested = m_NumberOfPixelsInRegion;
    }
  }
  [[nodiscard]] SizeValueType
  GetNumberOfSamples() const
  {
    return m_NumberOfSamplesRequested;
  }


  void
  ReinitializeSeed();

  void
  ReinitializeSeed(int);
 
private:
  void
  UpdatePosition();
 
  SizeValueType       m_NumberOfSamplesRequested{};
  SizeValueType       m_NumberOfSamplesDone{};
  SizeValueType       m_NumberOfPixelsInRegion{};
  RandomPermutation * m_Permutation{};
};
 
// Deduction guide for class template argument deduction (CTAD).
template <typename TImage>
ImageRandomNonRepeatingConstIteratorWithIndex(SmartPointer<TImage>, const typename TImage::RegionType &)
  -> ImageRandomNonRepeatingConstIteratorWithIndex<std::remove_const_t<TImage>>;
 
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkImageRandomNonRepeatingConstIteratorWithIndex.hxx"
#endif
 
#endif