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# RemoveIsolatedVertices

VTKEx/Cxx/Graphs/RemoveIsolatedVertices

Question

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### Code

RemoveIsolatedVertices.cxx

    #include <vtkSmartPointer.h>

    #include <vtkMutableUndirectedGraph.h>
    #include <vtkPoints.h>
    #include <vtkRemoveIsolatedVertices.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkMutableUndirectedGraph> g =
          vtkSmartPointer<vtkMutableUndirectedGraph>::New();

      // Create 3 vertices
      vtkIdType v1 = g->AddVertex();
      vtkIdType v2 = g->AddVertex();
      g->AddVertex();

      g->AddEdge ( v1, v2 );

      std::cout << "Graph has "
                << g->GetNumberOfVertices()
                << " vertices and "
                << g->GetNumberOfEdges() << " edge before." << std::endl;

      vtkSmartPointer<vtkRemoveIsolatedVertices> filter =
        vtkSmartPointer<vtkRemoveIsolatedVertices>::New();
      filter->SetInputConnection(g->GetProducerPort());
      filter->Update();

      std::cout << "Graph has "
                << filter->GetOutput()->GetNumberOfVertices()
                << " vertices and "
                << filter->GetOutput()->GetNumberOfEdges()
                << " edge after." << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(RemoveIsolatedVertices)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkInfovisCore QUIET)
    if (NOT VTK_FOUND)
      message("Skipping RemoveIsolatedVertices: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(RemoveIsolatedVertices MACOSX_BUNDLE RemoveIsolatedVertices.cxx )
      target_link_libraries(RemoveIsolatedVertices PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(RemoveIsolatedVertices MACOSX_BUNDLE RemoveIsolatedVertices.cxx )
      target_link_libraries(RemoveIsolatedVertices PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS RemoveIsolatedVertices
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build RemoveIsolatedVertices

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

    cd RemoveIsolatedVertices/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:

    ./RemoveIsolatedVertices

WINDOWS USERS

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