# EdgeWeights

VTKExamples/Cxx/Graphs/EdgeWeights

### Code

EdgeWeights.cxx

    #include <vtkSmartPointer.h>
    #include <vtkDataSetAttributes.h>
    #include <vtkDoubleArray.h>
    #include <vtkMutableUndirectedGraph.h>
    #include <vtkCircularLayoutStrategy.h>
    #include <vtkDoubleArray.h>
    #include <vtkGraphLayoutView.h>
    #include <vtkIntArray.h>
    #include <vtkMutableUndirectedGraph.h>
    #include <vtkRenderWindowInteractor.h>

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

      // Create 3 vertices
      vtkIdType v1 = g->AddVertex();
      vtkIdType v2 = g->AddVertex();
      vtkIdType v3 = g->AddVertex();

      // Create a fully connected graph
      g->AddEdge(v1, v2);
      g->AddEdge(v2, v3);
      g->AddEdge(v1, v3);

      // Create the edge weight array
      vtkSmartPointer<vtkDoubleArray> weights =
        vtkSmartPointer<vtkDoubleArray>::New();
      weights->SetNumberOfComponents(1);
      weights->SetName("Weights");

      // Set the edge weights
      weights->InsertNextValue(1.0);
      weights->InsertNextValue(1.0);
      weights->InsertNextValue(2.0);

      // Add the edge weight array to the graph
      g->GetEdgeData()->AddArray(weights);

      std::cout << "Number of Weights: "
                << vtkDoubleArray::SafeDownCast(
                  g->GetEdgeData()->GetArray("Weights"))->GetNumberOfTuples()
                << std::endl;

      for(vtkIdType i = 0; i < weights->GetNumberOfTuples(); i++)
      {
        double w = weights->GetValue(i);
        std::cout << "Weight " << i << " : " << w << std::endl;
      }

      vtkSmartPointer<vtkGraphLayoutView> graphLayoutView =
        vtkSmartPointer<vtkGraphLayoutView>::New();
      graphLayoutView->AddRepresentationFromInput(g);
      graphLayoutView->SetEdgeLabelVisibility(true);
      graphLayoutView->SetEdgeLabelArrayName("Weights");
      graphLayoutView->ResetCamera();
      graphLayoutView->Render();
      graphLayoutView->GetInteractor()->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(EdgeWeights)

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

    add_executable(EdgeWeights MACOSX_BUNDLE EdgeWeights.cxx )

    target_link_libraries(EdgeWeights ${VTK_LIBRARIES})

### Download and Build EdgeWeights

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

    cd EdgeWeights/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:

    ./EdgeWeights

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.