# ArrayCalculator

VTKExamples/Cxx/Utilities/ArrayCalculator

### Code

ArrayCalculator.cxx

    #include <vtkVersion.h>
    #include <vtkArrayCalculator.h>
    #include <vtkDoubleArray.h>
    #include <vtkPointData.h>
    #include <vtkPolyData.h>
    #include <vtkSmartPointer.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(1.0, 0.0, 0.0);
      points->InsertNextPoint(2.0, 0.0, 0.0);
      points->InsertNextPoint(3.0, 0.0, 0.0);

      vtkSmartPointer<vtkDoubleArray> array =
          vtkSmartPointer<vtkDoubleArray>::New();
      array->SetName("orig");
      array->InsertNextValue(1.0);
      array->InsertNextValue(2.0);
      array->InsertNextValue(3.0);

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

      vtkSmartPointer<vtkArrayCalculator> calc1 =
          vtkSmartPointer<vtkArrayCalculator>::New();
    #if VTK_MAJOR_VERSION <= 5
      calc1->SetInput(polydata);
    #else
      calc1->SetInputData(polydata);
    #endif
      calc1->AddScalarArrayName("orig");
      calc1->SetFunction("orig+1");
      calc1->SetResultArrayName("orig");
      calc1->Update();

      vtkSmartPointer<vtkDoubleArray> output1 =
        vtkDoubleArray::SafeDownCast(
          calc1->GetPolyDataOutput()->GetPointData()->GetArray("orig"));

      for(vtkIdType i = 0; i < output1->GetNumberOfTuples(); i++)
      {
        double val = output1->GetValue(i);
        cout << "output1 value " << i << ": " << val << endl;
      }

      vtkSmartPointer<vtkArrayCalculator> calc2 =
          vtkSmartPointer<vtkArrayCalculator>::New();
    #if VTK_MAJOR_VERSION <= 5
      calc2->SetInput(polydata);
    #else
      calc2->SetInputData(polydata);
    #endif
      calc2->AddScalarArrayName("orig");
      calc2->SetFunction("if(orig=2,1,orig)");
      calc2->SetResultArrayName("new");
      calc2->Update();

      vtkSmartPointer<vtkDoubleArray> output2 =
        vtkDoubleArray::SafeDownCast(
          calc2->GetPolyDataOutput()->GetPointData()->GetArray("new"));

      for(vtkIdType i = 0; i < output2->GetNumberOfTuples(); i++)
      {
        double val = output2->GetValue(i);
        cout << "output2 value " << i << ": " << val << endl;
      }

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ArrayCalculator)

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

    add_executable(ArrayCalculator MACOSX_BUNDLE ArrayCalculator.cxx )

    target_link_libraries(ArrayCalculator ${VTK_LIBRARIES})

### Download and Build ArrayCalculator

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

    cd ArrayCalculator/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:

    ./ArrayCalculator

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