[vtkusers] vtk Graph - Extracting a Subgraph

[Jeff Baumes]

Dirk,

1. vtkBoostBreadthFirstSearch will create an integer array "BFS" on the
vertices, the distance from the starting point. You can set the starting
vertex on the filter.
2. Create a vtkSelection representing a threshold 0-2 on the "BFS" array.
Something along the lines of:

vtkIntArray* arr = vtkIntArray::New();
arr->InsertNextValue(0);
arr->InsertNextValue(2);
arr->SetName("BFS");
vtkSelectionNode* node = vtkSelectionNode::New();
node->SetContentType(vtkSelectionNode::THRESHOLDS);
node->SetFieldType(vtkSelectionNode::VERTICES);
node->SetSelectionList(arr);
vtkSelection* sel = vtkSelection::New();
sel->AddNode(node);

See the source article here

http://kitware.com/products/thesource/apr2009.html

for more details on vtkSelection.

3. Use vtkExtractSelectedGraph, first input the output of the BFS filter,
second input the selection.

HTH,
Jeff

On Wed, Aug 5, 2009 at 3:20 PM, Dirk VanBruggen <dirk.c.vanbruggen at gmail.com
> wrote:

> Dear All,
>
> I am trying to find a way to take a graph, and extract a subgraph that
> contains a given vertex and all vertices within two hops of the given
> vertex.  Is there a boost algorithm or a different way to accomplish this?
>
> Thank you in advance for all of your help.
>
> Regards,
> Dirk
>
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