itkDistanceMetric.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 itkDistanceMetric_h
#define itkDistanceMetric_h
 
#include "itkFunctionBase.h"
#include "itkMeasurementVectorTraits.h"
 
namespace itk::Statistics
{
 
template <typename TVector>
class ITK_TEMPLATE_EXPORT DistanceMetric : public FunctionBase<TVector, double>
{
public:
  using Self = DistanceMetric;
  using Superclass = FunctionBase<TVector, double>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  using MeasurementVectorType = TVector;


  using MeasurementVectorSizeType = unsigned int;

  itkOverrideGetNameOfClassMacro(DistanceMetric);
 
  using OriginType = Array<double>;

  void
  SetOrigin(const OriginType & x);
 
  itkGetConstReferenceMacro(Origin, OriginType);

  double
  Evaluate(const MeasurementVectorType & x) const override = 0;

  virtual double
  Evaluate(const MeasurementVectorType & x1, const MeasurementVectorType & x2) const = 0;

  virtual void
  SetMeasurementVectorSize(MeasurementVectorSizeType s)
  {
    // Test whether the vector type is resizable or not
    if (MeasurementVectorTraits::IsResizable<MeasurementVectorType>({}))
    {
      // then this is a resizable vector type
      //
      // if the new size is the same as the previous size, just return
      if (s == this->m_MeasurementVectorSize)
      {
        return;
      }
 
      this->m_MeasurementVectorSize = s;
      this->Modified();
    }
    else
    {
      // If this is a non-resizable vector type
      const MeasurementVectorSizeType defaultLength = NumericTraits<MeasurementVectorType>::GetLength({});
      // and the new length is different from the default one, then throw an
      // exception
      if (defaultLength != s)
      {
        itkExceptionMacro("Attempting to change the measurement vector size of a non-resizable vector type");
      }
    }
  }

  itkGetConstMacro(MeasurementVectorSize, MeasurementVectorSizeType);
 
protected:
  DistanceMetric();
  ~DistanceMetric() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
private:
  OriginType m_Origin{};

  MeasurementVectorSizeType m_MeasurementVectorSize{};
}; // end of class
} // namespace itk::Statistics
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkDistanceMetric.hxx"
#endif
 
#endif