# LabelVerticesAndEdges

VTKExamples/Cxx/Graphs/LabelVerticesAndEdges

### Description

This example sets and displays labels of vertices and edges of a graph.

### Code

LabelVerticesAndEdges.cxx

    #include <vtkSmartPointer.h>

    #include <vtkCircularLayoutStrategy.h>
    #include <vtkDataSetAttributes.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);

      // Create an array for the vertex labels
      vtkSmartPointer<vtkIntArray> vertexIDs =
        vtkSmartPointer<vtkIntArray>::New();
      vertexIDs->SetNumberOfComponents(1);
      vertexIDs->SetName("VertexIDs");

      // Set the vertex labels
      vertexIDs->InsertNextValue(0);
      vertexIDs->InsertNextValue(1);
      vertexIDs->InsertNextValue(2);

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

      vtkSmartPointer<vtkCircularLayoutStrategy> circularLayoutStrategy =
        vtkSmartPointer<vtkCircularLayoutStrategy>::New();

      vtkSmartPointer<vtkGraphLayoutView> graphLayoutView =
        vtkSmartPointer<vtkGraphLayoutView>::New();
      graphLayoutView->AddRepresentationFromInput(g);

      graphLayoutView->SetLayoutStrategy(circularLayoutStrategy);
      graphLayoutView->SetVertexLabelVisibility(true);
      graphLayoutView->SetEdgeLabelVisibility(true);
      graphLayoutView->SetEdgeLabelArrayName("Weights"); //default is "labels"
      graphLayoutView->SetVertexLabelArrayName("VertexIDs"); //default is "labels"
      graphLayoutView->ResetCamera();
      graphLayoutView->Render();
      graphLayoutView->GetInteractor()->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(LabelVerticesAndEdges)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkInfovisLayout
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2
      vtkViewsInfovis QUIET)
    if (NOT VTK_FOUND)
      message("Skipping LabelVerticesAndEdges: ${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(LabelVerticesAndEdges MACOSX_BUNDLE LabelVerticesAndEdges.cxx )
      target_link_libraries(LabelVerticesAndEdges PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(LabelVerticesAndEdges MACOSX_BUNDLE LabelVerticesAndEdges.cxx )
      target_link_libraries(LabelVerticesAndEdges PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS LabelVerticesAndEdges
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build LabelVerticesAndEdges

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

    cd LabelVerticesAndEdges/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:

    ./LabelVerticesAndEdges

WINDOWS USERS

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