[vtkusers] Strange results with MST filter

[David Doria]

>
> Jeff,
>
> Trying another algorithm is a good idea. I'm curious why Kruskal's
> algorithm is a vtkSelectionAlgorithm subclass, while Prim's algorithm
> is a vtkTreeAlgorithm subclass? Wouldn't it be nice to be able to
> exchange the two directly?
>
> Trying to get Kruskal's algorithm working, I tried this:
>
>  vtkSmartPointer<vtkBoostKruskalMinimumSpanningTree> kruskalFilter =
>     vtkSmartPointer<vtkBoostKruskalMinimumSpanningTree>::New();
>  kruskalFilter->SetInputConnection(reader->GetOutputPort());
>  kruskalFilter->SetEdgeWeightArrayName("Weights");
>  kruskalFilter->Update();
>
>  vtkSmartPointer<vtkExtractSelection> extractSelection =
>      vtkSmartPointer<vtkExtractSelection>::New();
>  extractSelection->SetInput(0, reader->GetOutput());
>  extractSelection->SetInput(1, kruskalFilter->GetOutput());
>  extractSelection->Update();
>
>  cout << "selection output is type: " <<
> extractSelection->GetOutput()->GetClassName() << endl;
>
>  //output information about the minimum spanning tree
>  vtkDataObject* dataObject = extractSelection->GetOutput();
>  vtkGraph* mst = vtkGraph::SafeDownCast(dataObject);
>
> I tried to cast this 'dataObject' to a vtkGraph and a vtkTree, and
> both failed (mst was NULL).
>
> How would I get the Kruskal MST into a vtkTree?
>
> Thanks,
>
> David
>

Any thoughts on this?

Thanks,

David
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