# MinimumSpanningTree

VTKExamples/Cxx/Graphs/MinimumSpanningTree

### Description¶

This example shows how to find the minimum spanning tree. The input graph is:

and the minimum spanning tree computed is :

You must have compiled VTK with VTK_USE_BOOST=ON to use this functionality. You must also link to vtkInfovis.

Question

### Code¶

MinimumSpanningTree.cxx

#include <vtkSmartPointer.h>

#include <vtkBoostPrimMinimumSpanningTree.h>
#include <vtkDataSetAttributes.h>
#include <vtkDoubleArray.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkTree.h>

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

// Create 3 vertices

// Create a fully connected graph

// 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

// Output original graph info
std::cout << "Number of vertices: "
<< g->GetNumberOfVertices() << std::endl;
std::cout << "Number of edges: "
<< g->GetNumberOfEdges() << std::endl;
g->Dump();

// Setup the minimum spanning tree filter
vtkSmartPointer<vtkBoostPrimMinimumSpanningTree> minimumSpanningTreeFilter =
vtkSmartPointer<vtkBoostPrimMinimumSpanningTree>::New();
minimumSpanningTreeFilter->SetOriginVertex(v1);
minimumSpanningTreeFilter->SetInput(g);
minimumSpanningTreeFilter->SetEdgeWeightArrayName("Weights");

// Compute the minimum spanning tree
minimumSpanningTreeFilter->Update();

// Get the output tree
vtkSmartPointer<vtkTree> minimumSpanningTree = vtkSmartPointer<vtkTree>::New();
minimumSpanningTree->ShallowCopy(minimumSpanningTreeFilter->GetOutput());

// Output information about the minimum spanning tree
std::cout << "Number of vertices: "
<< minimumSpanningTree->GetNumberOfVertices() << std::endl;
std::cout << "Number of edges: "
<< minimumSpanningTree->GetNumberOfEdges() << std::endl;
minimumSpanningTree->Dump();

return EXIT_SUCCESS;
}


### CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(MinimumSpanningTree)

find_package(VTK COMPONENTS
vtkCommonCore
vtkCommonDataModel
vtkInfovisBoostGraphAlgorithms QUIET)
if (NOT VTK_FOUND)
message("Skipping MinimumSpanningTree: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(MinimumSpanningTree MACOSX_BUNDLE MinimumSpanningTree.cxx ) target_link_libraries(MinimumSpanningTree PRIVATE${VTK_LIBRARIES})
else ()
# include all components
target_link_libraries(MinimumSpanningTree PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS MinimumSpanningTree MODULES${VTK_LIBRARIES}
)
endif ()


cd MinimumSpanningTree/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:

./MinimumSpanningTree


WINDOWS USERS

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