itkRegularStepGradientDescentBaseOptimizer.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 itkRegularStepGradientDescentBaseOptimizer_h
#define itkRegularStepGradientDescentBaseOptimizer_h
 
#include "itkIntTypes.h"
#include "itkSingleValuedNonLinearOptimizer.h"
#include "ITKOptimizersExport.h"
 
namespace itk
{
class RegularStepGradientDescentBaseOptimizerEnums
{
public:
  enum class StopCondition : uint8_t
  {
    GradientMagnitudeTolerance = 1,
    StepTooSmall = 2,
    ImageNotAvailable = 3,
    CostFunctionError = 4,
    MaximumNumberOfIterations = 5,
    Unknown = 6
  };
};
// Define how to print enumeration
extern ITKOptimizers_EXPORT std::ostream &
operator<<(std::ostream & out, const RegularStepGradientDescentBaseOptimizerEnums::StopCondition value);

class ITKOptimizers_EXPORT RegularStepGradientDescentBaseOptimizer : public SingleValuedNonLinearOptimizer
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(RegularStepGradientDescentBaseOptimizer);

  using Self = RegularStepGradientDescentBaseOptimizer;
  using Superclass = SingleValuedNonLinearOptimizer;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkNewMacro(Self);

  itkOverrideGetNameOfClassMacro(RegularStepGradientDescentBaseOptimizer);
 
  using StopConditionEnum = RegularStepGradientDescentBaseOptimizerEnums::StopCondition;
#if !defined(ITK_LEGACY_REMOVE)
  // We need to expose the enum values at the class level
  // for backwards compatibility
  static constexpr StopConditionEnum GradientMagnitudeTolerance = StopConditionEnum::GradientMagnitudeTolerance;
  static constexpr StopConditionEnum StepTooSmall = StopConditionEnum::StepTooSmall;
  static constexpr StopConditionEnum ImageNotAvailable = StopConditionEnum::ImageNotAvailable;
  static constexpr StopConditionEnum CostFunctionError = StopConditionEnum::CostFunctionError;
  static constexpr StopConditionEnum MaximumNumberOfIterations = StopConditionEnum::MaximumNumberOfIterations;
  static constexpr StopConditionEnum Unknown = StopConditionEnum::Unknown;
#endif
  itkSetMacro(Maximize, bool);
  itkGetConstReferenceMacro(Maximize, bool);
  itkBooleanMacro(Maximize);
  bool
  GetMinimize() const
  {
    return !m_Maximize;
  }
  void
  SetMinimize(bool v)
  {
    this->SetMaximize(!v);
  }
  void
  MinimizeOn()
  {
    SetMaximize(false);
  }
  void
  MinimizeOff()
  {
    SetMaximize(true);
  }


  void
  StartOptimization() override;

  void
  ResumeOptimization();

  void
  StopOptimization();

  itkSetMacro(MaximumStepLength, double);
  itkSetMacro(MinimumStepLength, double);
  itkSetMacro(RelaxationFactor, double);
  itkSetMacro(NumberOfIterations, SizeValueType);
  itkSetMacro(GradientMagnitudeTolerance, double);
  itkGetConstReferenceMacro(CurrentStepLength, double);
  itkGetConstReferenceMacro(MaximumStepLength, double);
  itkGetConstReferenceMacro(MinimumStepLength, double);
  itkGetConstReferenceMacro(RelaxationFactor, double);
  itkGetConstReferenceMacro(NumberOfIterations, SizeValueType);
  itkGetConstReferenceMacro(GradientMagnitudeTolerance, double);
  itkGetConstMacro(CurrentIteration, unsigned int);
  itkGetConstReferenceMacro(StopCondition, StopConditionEnum);
  itkGetConstReferenceMacro(Value, MeasureType);
  itkGetConstReferenceMacro(Gradient, DerivativeType);

  std::string
  GetStopConditionDescription() const override;
 
protected:
  RegularStepGradientDescentBaseOptimizer();
  ~RegularStepGradientDescentBaseOptimizer() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;

  virtual void
  AdvanceOneStep();

  virtual void
  StepAlongGradient(double, const DerivativeType &)
  {
    ExceptionObject ex;
 
    ex.SetLocation(__FILE__);
    ex.SetDescription("This method MUST be overloaded in derived classes");
    throw ex;
  }
 
private:
protected:
  DerivativeType m_Gradient{};
  DerivativeType m_PreviousGradient{};
 
  bool               m_Stop{ false };
  bool               m_Maximize{};
  MeasureType        m_Value{};
  double             m_GradientMagnitudeTolerance{};
  double             m_MaximumStepLength{};
  double             m_MinimumStepLength{};
  double             m_CurrentStepLength{};
  double             m_RelaxationFactor{};
  StopConditionEnum  m_StopCondition{};
  SizeValueType      m_NumberOfIterations{};
  SizeValueType      m_CurrentIteration{};
  std::ostringstream m_StopConditionDescription{};
};
} // end namespace itk
 
#endif