itkExpectationMaximizationMixtureModelEstimator.h

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 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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 itkExpectationMaximizationMixtureModelEstimator_h
#define itkExpectationMaximizationMixtureModelEstimator_h

#include "itkMixtureModelComponentBase.h"
#include "itkGaussianMembershipFunction.h"
#include "itkSimpleDataObjectDecorator.h"

namespace itk
{
namespace Statistics
{
template< typename TSample >
class ITK_TEMPLATE_EXPORT ExpectationMaximizationMixtureModelEstimator:public Object
{
public:
  using Self = ExpectationMaximizationMixtureModelEstimator;
  using Superclass = Object;
  using Pointer = SmartPointer< Self >;
  using ConstPointer = SmartPointer< const Self >;

  itkTypeMacro(ExpectationMaximizationMixtureModelEstimator,
               Object);
  itkNewMacro(Self);

  using SampleType = TSample;
  using MeasurementType = typename TSample::MeasurementType;
  using MeasurementVectorType = typename TSample::MeasurementVectorType;

  using GaussianMembershipFunctionType = GaussianMembershipFunction<MeasurementVectorType>;

  using GaussianMembershipFunctionPointer = typename GaussianMembershipFunctionType::Pointer;

  using MembershipFunctionType = MembershipFunctionBase< MeasurementVectorType >;
  using MembershipFunctionPointer = typename MembershipFunctionType::ConstPointer;
  using MembershipFunctionVectorType = std::vector< MembershipFunctionPointer >;
  using MembershipFunctionVectorObjectType = SimpleDataObjectDecorator<MembershipFunctionVectorType>;
  using MembershipFunctionVectorObjectPointer = typename MembershipFunctionVectorObjectType::Pointer;

  using ComponentType = MixtureModelComponentBase< TSample >;

  using ComponentVectorType = std::vector< ComponentType * >;

  using ComponentMembershipFunctionType = MembershipFunctionBase<MeasurementVectorType>;

  using ProportionVectorType = Array< double >;

  void SetSample(const TSample *sample);

  const TSample * GetSample() const;

  void SetInitialProportions(ProportionVectorType & propotion);

  const ProportionVectorType & GetInitialProportions() const;

  const ProportionVectorType & GetProportions() const;

  using MembershipFunctionsWeightsArrayObjectType = SimpleDataObjectDecorator<ProportionVectorType>;
  using MembershipFunctionsWeightsArrayPointer = typename MembershipFunctionsWeightsArrayObjectType::Pointer;

  const MembershipFunctionsWeightsArrayObjectType * GetMembershipFunctionsWeightsArray() const;

  void SetMaximumIteration(int numberOfIterations);

  int GetMaximumIteration() const;

  int GetCurrentIteration()
  {
    return m_CurrentIteration;
  }

  int AddComponent(ComponentType *component);

  unsigned int GetNumberOfComponents() const;

  void Update();

  enum TERMINATION_CODE { CONVERGED = 0, NOT_CONVERGED = 1 };

  TERMINATION_CODE GetTerminationCode() const;

  ComponentMembershipFunctionType * GetComponentMembershipFunction(int componentIndex) const;

  const MembershipFunctionVectorObjectType * GetOutput() const;

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

  bool CalculateDensities();

  double CalculateExpectation() const;

  bool UpdateComponentParameters();

  bool UpdateProportions();

  void GenerateData();

private:
  const TSample *m_Sample;

  int m_MaxIteration{100};
  int m_CurrentIteration{0};

  TERMINATION_CODE     m_TerminationCode;
  ComponentVectorType  m_ComponentVector;
  ProportionVectorType m_InitialProportions;
  ProportionVectorType m_Proportions;

  MembershipFunctionVectorObjectPointer  m_MembershipFunctionsObject;
  MembershipFunctionsWeightsArrayPointer m_MembershipFunctionsWeightArrayObject;
};  // end of class
} // end of namespace Statistics
} // end of namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkExpectationMaximizationMixtureModelEstimator.hxx"
#endif

#endif