RemoveIsolatedVertices

#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;
}

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 () 

cd RemoveIsolatedVertices/build 

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./RemoveIsolatedVertices