# KMeansClustering

VTKExamples/Cxx/InfoVis/KMeansClustering

### Description

This example clusters 3D points using the KMeans algorithm. The points are assigned to a cluster by creating an array with each point's cluster id.

### Code

KMeansClustering.cxx

    #include <vtkVersion.h>

    #include <vtkSmartPointer.h>
    #include <vtkProperty.h>
    #include <vtkPointData.h>
    #include <vtkPolyData.h>
    #include <vtkXMLPolyDataWriter.h>
    #include <vtkIntArray.h>
    #include <vtkMultiBlockDataSet.h>
    #include <vtkPoints.h>
    #include <vtkTable.h>
    #include <vtkDoubleArray.h>
    #include <vtkKMeansStatistics.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkVertexGlyphFilter.h>
    #include <vtkInteractorStyleTrackballCamera.h>

    #include <sstream>

    int main(int, char*[])
    {
      // Create 2 clusters, one near (0,0,0) and the other near (3,3,3)
      vtkSmartPointer<vtkPoints> points =
          vtkSmartPointer<vtkPoints>::New();

      points->InsertNextPoint ( 0.0, 0.0, 0.0 );
      points->InsertNextPoint ( 3.0, 3.0, 3.0 );
      points->InsertNextPoint ( 0.1, 0.1, 0.1 );
      points->InsertNextPoint ( 3.1, 3.1, 3.1 );
      points->InsertNextPoint ( 0.2, 0.2, 0.2 );
      points->InsertNextPoint ( 3.2, 3.2, 3.2 );

      // Get the points into the format needed for KMeans
      vtkSmartPointer<vtkTable> inputData =
          vtkSmartPointer<vtkTable>::New();

      for( int c = 0; c < 3; ++c )
      {
        std::stringstream colName;
        colName << "coord " << c;
        vtkSmartPointer<vtkDoubleArray> doubleArray =
          vtkSmartPointer<vtkDoubleArray>::New();
        doubleArray->SetNumberOfComponents(1);
        doubleArray->SetName( colName.str().c_str() );
        doubleArray->SetNumberOfTuples(points->GetNumberOfPoints());

        for( int r = 0; r < points->GetNumberOfPoints(); ++ r )
        {
          double p[3];
          points->GetPoint(r, p);

          doubleArray->SetValue( r, p[c] );
        }

        inputData->AddColumn( doubleArray );
      }

      vtkSmartPointer<vtkKMeansStatistics> kMeansStatistics =
        vtkSmartPointer<vtkKMeansStatistics>::New();

    #if VTK_MAJOR_VERSION <= 5
      kMeansStatistics->SetInput( vtkStatisticsAlgorithm::INPUT_DATA, inputData );
    #else
      kMeansStatistics->SetInputData( vtkStatisticsAlgorithm::INPUT_DATA, inputData );
    #endif
      kMeansStatistics->SetColumnStatus( inputData->GetColumnName( 0 ) , 1 );
      kMeansStatistics->SetColumnStatus( inputData->GetColumnName( 1 ) , 1 );
      kMeansStatistics->SetColumnStatus( inputData->GetColumnName( 2 ) , 1 );
      //kMeansStatistics->SetColumnStatus( "Testing", 1 );
      kMeansStatistics->RequestSelectedColumns();
      kMeansStatistics->SetAssessOption( true );
      kMeansStatistics->SetDefaultNumberOfClusters( 2 );
      kMeansStatistics->Update() ;

      // Display the results
      kMeansStatistics->GetOutput()->Dump();

      vtkSmartPointer<vtkIntArray> clusterArray =
        vtkSmartPointer<vtkIntArray>::New();
      clusterArray->SetNumberOfComponents(1);
      clusterArray->SetName( "ClusterId" );

      for(int r = 0; r < kMeansStatistics->GetOutput()->GetNumberOfRows(); r++)
      {
        vtkVariant v = kMeansStatistics->GetOutput()->GetValue(r,kMeansStatistics->GetOutput()->GetNumberOfColumns() - 1);
        std::cout << "Point " << r << " is in cluster " << v.ToInt() << std::endl;
        clusterArray->InsertNextValue(v.ToInt());
      }

    /*

      // Output the cluster centers

      vtkMultiBlockDataSet* outputMetaDS = vtkMultiBlockDataSet::SafeDownCast( kMeansStatistics->GetOutputDataObject( vtkStatisticsAlgorithm::OUTPUT_MODEL ) );
      vtkSmartPointer<vtkTable> outputMeta = vtkTable::SafeDownCast( outputMetaDS->GetBlock( 0 ) );
      //vtkSmartPointer<vtkTable> outputMeta = vtkTable::SafeDownCast( outputMetaDS->GetBlock( 1 ) );
      vtkDoubleArray* coord0 = vtkDoubleArray::SafeDownCast(outputMeta->GetColumnByName("coord 0"));
      vtkDoubleArray* coord1 = vtkDoubleArray::SafeDownCast(outputMeta->GetColumnByName("coord 1"));
      vtkDoubleArray* coord2 = vtkDoubleArray::SafeDownCast(outputMeta->GetColumnByName("coord 2"));

      for(unsigned int i = 0; i < coord0->GetNumberOfTuples(); ++i)
        {
        std::cout << coord0->GetValue(i) << " " << coord1->GetValue(i) << " " << coord2->GetValue(i) << std::endl;
        }
    */

      vtkSmartPointer<vtkPolyData> polydata =
        vtkSmartPointer<vtkPolyData>::New();
      polydata->SetPoints(points);
      //polydata->GetPointData()->AddArray(clusterArray);
      polydata->GetPointData()->SetScalars(clusterArray);

      vtkSmartPointer<vtkXMLPolyDataWriter> writer =
        vtkSmartPointer<vtkXMLPolyDataWriter>::New();
      writer->SetFileName("output.vtp");
    #if VTK_MAJOR_VERSION <= 5
      writer->SetInputConnection(polydata->GetProducerPort());
    #else
      writer->SetInputData(polydata);
    #endif
      writer->Write();

      // Display
      vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter =
        vtkSmartPointer<vtkVertexGlyphFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
      glyphFilter->SetInputConnection(polydata->GetProducerPort());
    #else
      glyphFilter->SetInputData(polydata);
    #endif
      glyphFilter->Update();

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> mapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(glyphFilter->GetOutputPort());

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetPointSize(3);

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Add the actor to the scene
      renderer->AddActor(actor);
      //renderer->SetBackground(.3, .6, .3); // Background color green

      vtkSmartPointer<vtkInteractorStyleTrackballCamera> style =
        vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
      renderWindowInteractor->SetInteractorStyle( style );

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(KMeansClustering)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(KMeansClustering MACOSX_BUNDLE KMeansClustering.cxx )

    target_link_libraries(KMeansClustering ${VTK_LIBRARIES})

### Download and Build KMeansClustering

Click here to download KMeansClustering and its CMakeLists.txt file. Once the tarball KMeansClustering.tar has been downloaded and extracted,

    cd KMeansClustering/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:

    ./KMeansClustering

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.