ITK  4.8.0 Insight Segmentation and Registration Toolkit
Examples/Statistics/EuclideanDistanceMetric.cxx
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// Software Guide : BeginLatex
//
// \index{itk::Statistics::EuclideanDistanceMetric}
//
// The Euclidean distance function (\subdoxygen{Statistics}{EuclideanDistanceMetric}
// requires as template parameter the type of the measurement vector. We can
// use this function for any subclass of the \doxygen{FixedArray}. As a
// subclass of the \subdoxygen{Statistics}{DistanceMetric}, it has two basic
// methods, the \code{SetOrigin(measurement vector)} and the
// \code{Evaluate(measurement vector)}. The \code{Evaluate()} method returns
// the distance between its argument (a measurement vector) and the measurement
// vector set by the \code{SetOrigin()} method.
//
// In addition to the two methods, EuclideanDistanceMetric has two more
// methods that return the distance of two measurements ---
// \code{Evaluate(measurement vector, measurement vector)} and the
// coordinate distance between two measurements (not vectors) ---
// \code{Evaluate(measurement, measurement)}. The argument type of the
// latter method is the type of the component of the measurement vector.
//
// We include the header files for the class and the \doxygen{Vector}.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "itkVector.h"
#include "itkArray.h"
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We define the type of the measurement vector that will be input of
// the Euclidean distance function. As a result, the measurement type
// is \code{float}.
//
// Software Guide : EndLatex
int main(int, char*[])
{
// Software Guide : BeginCodeSnippet
typedef itk::Array< float > MeasurementVectorType;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The instantiation of the function is done through the usual
// \code{New()} method and a smart pointer.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
DistanceMetricType;
DistanceMetricType::Pointer distanceMetric = DistanceMetricType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We create three measurement vectors, the \code{originPoint},
// the \code{queryPointA}, and the \code{queryPointB}. The type of the
// \code{originPoint} is fixed in the
// \subdoxygen{Statistics}{DistanceMetric} base class as
// \code{itk::Vector< double, length of the measurement vector of the
// each distance metric instance>}.
//
// Software Guide : EndLatex
// Software Guide : BeginLatex
//
// The Distance metric does not know about the length of the measurement
// vectors. We must set it explicitly using the
// \code{SetMeasurementVectorSize()} method.
//
// Software Guide : EndLatex
distanceMetric->SetMeasurementVectorSize( 2 );
// Software Guide : BeginCodeSnippet
DistanceMetricType::OriginType originPoint( 2 );
MeasurementVectorType queryPointA( 2 );
MeasurementVectorType queryPointB( 2 );
originPoint[0] = 0;
originPoint[1] = 0;
queryPointA[0] = 2;
queryPointA[1] = 2;
queryPointB[0] = 3;
queryPointB[1] = 3;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// In the following code snippet, we show the uses of the three different
// \code{Evaluate()} methods.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
distanceMetric->SetOrigin( originPoint );
std::cout << "Euclidean distance between the origin and the query point A = "
<< distanceMetric->Evaluate( queryPointA )
<< std::endl;
std::cout << "Euclidean distance between the two query points (A and B) = "
<< distanceMetric->Evaluate( queryPointA, queryPointB )
<< std::endl;
std::cout << "Coordinate distance between "
<< "the first components of the two query points = "
<< distanceMetric->Evaluate( queryPointA[0], queryPointB[0] )
<< std::endl;
// Software Guide : EndCodeSnippet
return 0;
}