ArrayLookup

#include <vtkSmartPointer.h>
#include <vtkFloatArray.h>
#include <vtkIdList.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkFloatArray> distances =
    vtkSmartPointer<vtkFloatArray>::New();
  distances->SetNumberOfComponents(1);
  distances->SetName("Distances");

  distances->InsertNextValue(5);
  distances->InsertNextValue(15);
  distances->InsertNextValue(15);
  distances->InsertNextValue(25);
  distances->InsertNextValue(15);

  // Get first location
  vtkIdType result = distances->LookupValue(15);
  std::cout << "result: " << result << std::endl;

  // Get all locations
  vtkSmartPointer<vtkIdList> idList =
    vtkSmartPointer<vtkIdList>::New();
  distances->LookupValue(15, idList);
  std::cout << "found at: " << std::endl;
  for(vtkIdType i = 0; i < idList->GetNumberOfIds(); i++)
  {
    std::cout << idList->GetId(i) << " ";
  }

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ArrayLookup)

find_package(VTK COMPONENTS 
  vtkCommonCore QUIET)
if (NOT VTK_FOUND)
  message("Skipping ArrayLookup: ${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(ArrayLookup MACOSX_BUNDLE ArrayLookup.cxx )
  target_link_libraries(ArrayLookup PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ArrayLookup MACOSX_BUNDLE ArrayLookup.cxx )
  target_link_libraries(ArrayLookup PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ArrayLookup
    MODULES ${VTK_LIBRARIES}
    )
endif () 

cd ArrayLookup/build 

cmake ..

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

make

./ArrayLookup