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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
{
namespace Statistics
{
/**
* \class DistanceMetric
* \brief this class declares common interfaces
* for distance functions.
*
* As a function derived from FunctionBase, users use Evaluate method to get
* result.
*
* To use this function users should first set the origin by calling
* SetOrigin() function, then call Evaluate() method with a point to get the
* distance between the origin point and the evaluation point.
*
* \sa EuclideanSquareDistanceMetric
* \sa EuclideanDistanceMetric
* \sa ManhattanDistanceMetric
*
* \ingroup ITKStatistics
*/
template <typename TVector>
class ITK_TEMPLATE_EXPORT DistanceMetric : public FunctionBase<TVector, double>
{
public:
/** Standard type alias */
using Self = DistanceMetric;
using Superclass = FunctionBase<TVector, double>;
using Pointer = SmartPointer<Self>;
using ConstPointer = SmartPointer<const Self>;
/** declare the MeasurementVector type */
using MeasurementVectorType = TVector;
/** declare Measurement vector component type */
/** Type used to represent the number of components oft he
MeasurementVectorType */
using MeasurementVectorSizeType = unsigned int;
/** \see LightObject::GetNameOfClass() */
itkOverrideGetNameOfClassMacro(DistanceMetric);
using OriginType = Array<double>;
/** Sets the origin point that will be used for the single point version
* Evaluate() function. This function is necessary part of implementing the
* Evaluate() interface. The argument of SetOrigin() must be of type
* DistanceMetric::OriginType, which in most cases will be different from the
* TVector type. This is necessary because often times the origin would be a
* mean, or a vector representative of a collection of vectors. */
void
SetOrigin(const OriginType & x);
itkGetConstReferenceMacro(Origin, OriginType);
/** Gets the distance between the origin point and x. This function
* work with SetOrigin() function. */
double
Evaluate(const MeasurementVectorType & x) const override = 0;
/** Gets the distance between x1 and x2. This method is used by
* KdTreeKMeans estimators. When the estimator is refactored,
* this method should be removed. Distance between two measurement
* vectors can be computed by setting one of them as an origin of
* the distance and using the Evaluate method with a single argument */
virtual double
Evaluate(const MeasurementVectorType & x1, const MeasurementVectorType & x2) const = 0;
/** Set method for the length of the measurement vector */
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;
}
else
{
this->m_MeasurementVectorSize = s;
this->Modified();
}
}
else
{
// If this is a non-resizable vector type
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");
}
}
}
/** Get method for the length of the measurement vector */
itkGetConstMacro(MeasurementVectorSize, MeasurementVectorSizeType);
protected:
DistanceMetric();
~DistanceMetric() override = default;
void
PrintSelf(std::ostream & os, Indent indent) const override;
private:
OriginType m_Origin{};
/** Number of components in the MeasurementVectorType */
MeasurementVectorSizeType m_MeasurementVectorSize{};
}; // end of class
} // end of namespace Statistics
} // end of namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
# include "itkDistanceMetric.hxx"
#endif
#endif
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