# DetermineArrayDataTypes

VTKExamples/Cxx/PolyData/DetermineArrayDataTypes

### Description

This example shows how to determine the type of data stored in a named array in a vtp file.

### Code

DetermineArrayDataTypes.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPolyData.h>
    #include <vtkPointData.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vector>
    #include <string>

    void FindAllData(const std::string &inputFilename);

    int main(int argc, char *argv[])
    {
      if(argc != 2)
      {
        std::cout << "Usage: " << argv[0] << " InputFilename" << std::endl;
        return EXIT_FAILURE;
      }

      std::string inputFilename = argv[1];
      FindAllData(inputFilename);

      return EXIT_SUCCESS;
    }

    void FindAllData(const std::string &InputFilename)
    {
      vtkSmartPointer<vtkXMLPolyDataReader> reader =
        vtkSmartPointer<vtkXMLPolyDataReader>::New();
      reader->SetFileName(InputFilename.c_str());
      reader->Update();
      vtkPolyData* polydata = reader->GetOutput();

      unsigned int numberOfArrays = polydata->GetPointData()->GetNumberOfArrays();
      std::cout << "NumArrays: " << numberOfArrays << std::endl;

      std::cout << "key: " << std::endl;;
      //more values can be found in <VTK_DIR>/Common/vtkSetGet.h
      std::cout << VTK_UNSIGNED_CHAR << " unsigned char" << std::endl;
      std::cout << VTK_UNSIGNED_INT << " unsigned int" << std::endl;
      std::cout << VTK_FLOAT << " float" << std::endl;
      std::cout << VTK_DOUBLE << " double" << std::endl;

      std::vector<std::string> arrayNames;
      for(unsigned int i = 0; i < numberOfArrays; i++)
      {
        //the following two lines are equivalent
        //arrayNames.push_back(polydata->GetPointData()->GetArray(i)->GetName());
        arrayNames.push_back(polydata->GetPointData()->GetArrayName(i));
        int dataTypeID = polydata->GetPointData()->GetArray(i)->GetDataType();
        std::cout << "Array " << i << ": " << arrayNames[i] << " (type: " << dataTypeID << ")" << std::endl;
      }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(DetermineArrayDataTypes)

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

### Download and Build DetermineArrayDataTypes

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

    cd DetermineArrayDataTypes/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:

    ./DetermineArrayDataTypes

WINDOWS USERS

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