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¶
Danger
The generation of tar files has not been ported to the new VTKExamples. Some tarballs may be missing or out-of-date.
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.