PCAStatistics
VTKExamples/Cxx/Utilities/PCAStatistics
Code
PCAStatistics.cxx
#include <vtkVersion.h>
#include "vtkSmartPointer.h"
#include "vtkDoubleArray.h"
#include "vtkMultiBlockDataSet.h"
#include "vtkPCAStatistics.h"
#include "vtkStringArray.h"
#include "vtkTable.h"
int main(int, char*[])
{
// Each one of these arrays is a single component of
// the data. That is, if you have 3D spatial data (x,y,z)
// you need to construct an array of all the x values,
// an array of all the y values, and an array of all the
// z values.
// Construct a data set of 3 3D points.
// These would be all of your "x" values.
const char m0Name[] = "M0";
vtkSmartPointer<vtkDoubleArray> dataset1Arr =
vtkSmartPointer<vtkDoubleArray>::New();
dataset1Arr->SetNumberOfComponents(1);
dataset1Arr->SetName( m0Name );
dataset1Arr->InsertNextValue(0);
dataset1Arr->InsertNextValue(1);
dataset1Arr->InsertNextValue(0);
// These would be all of your "y" values.
const char m1Name[] = "M1";
vtkSmartPointer<vtkDoubleArray> dataset2Arr =
vtkSmartPointer<vtkDoubleArray>::New();
dataset2Arr->SetNumberOfComponents(1);
dataset2Arr->SetName( m1Name );
dataset2Arr->InsertNextValue(0);
dataset2Arr->InsertNextValue(0);
dataset2Arr->InsertNextValue(1);
// These would be all of your "z" values.
const char m2Name[] = "M2";
vtkSmartPointer<vtkDoubleArray> dataset3Arr =
vtkSmartPointer<vtkDoubleArray>::New();
dataset3Arr->SetNumberOfComponents(1);
dataset3Arr->SetName( m2Name );
dataset3Arr->InsertNextValue(0);
dataset3Arr->InsertNextValue(0);
dataset3Arr->InsertNextValue(0);
vtkSmartPointer<vtkTable> datasetTable =
vtkSmartPointer<vtkTable>::New();
datasetTable->AddColumn(dataset1Arr);
datasetTable->AddColumn(dataset2Arr);
datasetTable->AddColumn(dataset3Arr);
vtkSmartPointer<vtkPCAStatistics> pcaStatistics =
vtkSmartPointer<vtkPCAStatistics>::New();
#if VTK_MAJOR_VERSION <= 5
pcaStatistics->SetInput( vtkStatisticsAlgorithm::INPUT_DATA, datasetTable );
#else
pcaStatistics->SetInputData( vtkStatisticsAlgorithm::INPUT_DATA, datasetTable );
#endif
pcaStatistics->SetColumnStatus("M0", 1 );
pcaStatistics->SetColumnStatus("M1", 1 );
pcaStatistics->SetColumnStatus("M2", 1 );
pcaStatistics->RequestSelectedColumns();
pcaStatistics->SetDeriveOption(true);
pcaStatistics->Update();
///////// Eigenvalues ////////////
vtkSmartPointer<vtkDoubleArray> eigenvalues =
vtkSmartPointer<vtkDoubleArray>::New();
pcaStatistics->GetEigenvalues(eigenvalues);
// double eigenvaluesGroundTruth[3] = {.5, .166667, 0};
for(vtkIdType i = 0; i < eigenvalues->GetNumberOfTuples(); i++)
{
std::cout << "Eigenvalue " << i << " = " << eigenvalues->GetValue(i) << std::endl;
}
///////// Eigenvectors ////////////
vtkSmartPointer<vtkDoubleArray> eigenvectors =
vtkSmartPointer<vtkDoubleArray>::New();
pcaStatistics->GetEigenvectors(eigenvectors);
for(vtkIdType i = 0; i < eigenvectors->GetNumberOfTuples(); i++)
{
std::cout << "Eigenvector " << i << " : ";
double* evec = new double[eigenvectors->GetNumberOfComponents()];
eigenvectors->GetTuple(i, evec);
for(vtkIdType j = 0; j < eigenvectors->GetNumberOfComponents(); j++)
{
std::cout << evec[j] << " ";
vtkSmartPointer<vtkDoubleArray> eigenvectorSingle =
vtkSmartPointer<vtkDoubleArray>::New();
pcaStatistics->GetEigenvector(i, eigenvectorSingle);
}
delete[] evec;
std::cout << std::endl;
}
return EXIT_SUCCESS;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
PROJECT(PCAStatistics)
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
add_executable(PCAStatistics MACOSX_BUNDLE PCAStatistics.cxx)
target_link_libraries(PCAStatistics ${VTK_LIBRARIES})
Download and Build PCAStatistics
Click here to download PCAStatistics and its CMakeLists.txt file. Once the tarball PCAStatistics.tar has been downloaded and extracted,
cd PCAStatistics/build
If VTK is installed:
cmake ..
If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..
Build the project:
make
and run it:
./PCAStatistics
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.