ITK  5.3.0
Insight Toolkit
Examples/Statistics/MembershipSample.cxx
/*=========================================================================
*
* Copyright NumFOCUS
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* 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
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* http://www.apache.org/licenses/LICENSE-2.0.txt
*
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* 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
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// Software Guide : BeginLatex
//
// \index{itk::Statistics::MembershipSample}
//
// The \subdoxygen{Statistics}{MembershipSample} is derived from the class
// \subdoxygen{Statistics}{Sample} that associates a class label with each
// measurement vector. It needs another Sample object for storing measurement
// vectors. A \code{MembershipSample} object stores a subset of instance
// identifiers from another Sample object. \emph{Any} subclass of Sample can
// be the source Sample object. The MembershipSample class is useful for
// storing classification results from a test Sample object. The
// MembershipSample class can be considered as an associative container that
// stores measurement vectors, frequency values, and \emph{class labels}.
//
// To use a MembershipSample object, we include the header files for the
// class itself and the Sample class. We will use the
// \subdoxygen{Statistics}{ListSample} as the input sample. We need another
// header for measurement vectors. We are going to use the \doxygen{Vector}
// class which is a subclass of the \doxygen{FixedArray}.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "itkListSample.h"
#include "itkVector.h"
// Software Guide : EndCodeSnippet
int
main()
{
// Software Guide : BeginLatex
//
// The following code snippet will create a \code{ListSample} object
// with three-component float measurement vectors and put three
// measurement vectors in the \code{ListSample} object.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using MeasurementVectorType = itk::Vector<float, 3>;
SampleType::Pointer sample = SampleType::New();
MeasurementVectorType mv;
mv[0] = 1.0;
mv[1] = 2.0;
mv[2] = 4.0;
sample->PushBack(mv);
mv[0] = 2.0;
mv[1] = 4.0;
mv[2] = 5.0;
sample->PushBack(mv);
mv[0] = 3.0;
mv[1] = 8.0;
mv[2] = 6.0;
sample->PushBack(mv);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// To create a MembershipSample instance, we define the type of the
// MembershipSample using the source sample type using the previously
// defined \code{SampleType}. As usual, after that, we call the
// \code{New()} method to create an instance. We must plug in the source
// sample, Sample, using the \code{SetSample()} method. We provide class
// labels for data instances in the Sample object using the
// \code{AddInstance()} method. As the required initialization step for the
// \code{membershipSample}, we must call the \code{SetNumberOfClasses()}
// method with the number of classes. We must add all instances in the
// source sample with their class labels. In the following code snippet, we
// set the first instance' class label to 0, the second to 0, the third
// (last) to 1. After this, the \code{membershipSample} has two
// \code{Subsample} objects. And the class labels for these two
// \code{Subsample} objects are 0 and 1. The $0$ class \code{Subsample}
// object includes the first and second instances, and the $1$ class
// includes the third instance.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using MembershipSampleType = itk::Statistics::MembershipSample<SampleType>;
MembershipSampleType::Pointer membershipSample =
MembershipSampleType::New();
membershipSample->SetSample(sample);
membershipSample->SetNumberOfClasses(2);
membershipSample->AddInstance(0U, 0UL);
membershipSample->AddInstance(0U, 1UL);
membershipSample->AddInstance(1U, 2UL);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \code{Size()} and \code{GetTotalFrequency()} returns the same
// information that Sample does.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
std::cout << "Total frequency = " << membershipSample->GetTotalFrequency()
<< std::endl;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The \code{membershipSample} is ready for use. The following code snippet
// shows how to use the \code{Iterator} interface. The
// MembershipSample's \code{Iterator} has an additional method
// that returns the class label (\code{GetClassLabel()}).
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
MembershipSampleType::ConstIterator iter = membershipSample->Begin();
while (iter != membershipSample->End())
{
std::cout << "instance identifier = " << iter.GetInstanceIdentifier()
<< "\t measurement vector = " << iter.GetMeasurementVector()
<< "\t frequency = " << iter.GetFrequency()
<< "\t class label = " << iter.GetClassLabel() << std::endl;
++iter;
}
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// To see the numbers of instances in each class subsample, we use
// the \code{Size()} method of the \code{ClassSampleType} instance
// returned by the \code{GetClassSample(index)} method.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
std::cout << "class label = 0 sample size = "
<< membershipSample->GetClassSample(0)->Size() << std::endl;
std::cout << "class label = 1 sample size = "
<< membershipSample->GetClassSample(1)->Size() << std::endl;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We call the \code{GetClassSample()} method to get the
// class subsample in the \code{membershipSample}. The
// \code{MembershipSampleType::ClassSampleType} is actually a
// specialization of the \subdoxygen{Statistics}{Subsample}. We print
// out the instance identifiers, measurement vectors, and frequency
// values that are part of the class. The output will be two lines for
// the two instances that belong to the class $0$.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
MembershipSampleType::ClassSampleType::ConstPointer classSample =
membershipSample->GetClassSample(0);
MembershipSampleType::ClassSampleType::ConstIterator c_iter =
classSample->Begin();
while (c_iter != classSample->End())
{
std::cout << "instance identifier = " << c_iter.GetInstanceIdentifier()
<< "\t measurement vector = " << c_iter.GetMeasurementVector()
<< "\t frequency = " << c_iter.GetFrequency() << std::endl;
++c_iter;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}
itk::Statistics::MembershipSample
Container for storing the instance-identifiers of other sample with their associated class labels.
Definition: itkMembershipSample.h:57
itk::Vector
A templated class holding a n-Dimensional vector.
Definition: itkVector.h:62
itk::Statistics::ListSample
This class is the native implementation of the a Sample with an STL container.
Definition: itkListSample.h:51
itkMembershipSample.h
itkListSample.h
itkVector.h