[Paraview] Catalyst distributed graph example

[Jeff Baumes]

vtkMutableDirectedGraph
<https://www.vtk.org/doc/nightly/html/classvtkMutableDirectedGraph.html>
has an API that is hopefully pretty intuitive with AddVertex, AddEdge, etc.
You can also shallow-copy from the mutable graph into a DAG object, which
performs a check, if it is important to verify you made a proper DAG. From
the vtkDirectedAcyclicGraph docs
<https://www.vtk.org/doc/nightly/html/classvtkDirectedAcyclicGraph.html> (I
noticed some typos here, should read "DAG" instead of "tree"):

=====
vtkDirectedAcyclicGraph is a read-only data structure. To construct a tree,
create an instance of vtkMutableDirectedGraph. Add vertices and edges with
AddVertex() and AddEdge(). You may alternately start by adding a single
vertex as the root then call graph->AddChild(parent) which adds a new
vertex and connects the parent to the child. The tree MUST have all edges
in the proper direction, from parent to child. After building the tree,
call tree->CheckedShallowCopy(graph) to copy the structure into a
vtkDirectedAcyclicGraph. This method will return false if the graph is an
invalid tree.
=====

As for rendering in ParaView, you the following example shows how to use
vtkGraphToPolyData, but this is not exposed in ParaView to my knowledge, I
think you would need a plugin, or preprocess the graph into a vtkPolyData,
save it, then load into ParaView.

https://www.vtk.org/Wiki/VTK/Examples/Cxx/Graphs/GraphToPolyData

Embedding from higher-dimensional coordinates into 2D or 3D does not have a
VTK implementation that I know of, though PCA in VTK may be able to be
used. If you want to do layout based on edge connectivity, there are some graph
layout algorithms
<https://www.vtk.org/doc/nightly/html/classvtkGraphLayoutStrategy.html> in
VTK that could get you 2D or 3D coordinates.

HTH,
Jeff

On Wed, Sep 13, 2017 at 11:58 AM Andy Bauer <andy.bauer at kitware.com> wrote:

> Hi Matthieu,
>
> There isn't a Catalyst example for graphs but it shouldn't be too hard to
> make. I'm not very familiar with the vtkGraph and derived classes but if I
> were to to try doing that I'd just see how the graph object is generated in
> some filter that generates one (look in the RequestData() method).
>
> As for visualizing graphs in ParaView, hopefully someone else on the list
> can provide insight on doing that.
>
> Best,
> Andy
>
> On Wed, Sep 13, 2017 at 11:38 AM, Dorier, Matthieu <mdorier at anl.gov>
> wrote:
>
>> Hi,
>>
>>
>> I would like to use Catalyst to visualize a distributed directed graph.
>> Each node of the graph is characterized by an id (not necessarily
>> contiguous, as some nodes are added and removed during the execution) and a
>> list of connections (ids of "friends").
>>
>>
>> The nodes can be assigned coordinates in a 2D or a 3D space.
>>
>>
>> Do you have an example of adaptor for that?
>>
>>
>> Also if I want to use coordinates in higher dimensions, would I need to
>> project to a 3D subspace or is there a way for ParaView to figure out a
>> layout to display the graph?
>>
>>
>> Thanks,
>>
>>
>> Matthieu
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ParaView Wiki at:
>> http://paraview.org/Wiki/ParaView
>>
>> Search the list archives at: http://markmail.org/search/?q=ParaView
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/paraview
>>
>>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the ParaView Wiki at:
> http://paraview.org/Wiki/ParaView
>
> Search the list archives at: http://markmail.org/search/?q=ParaView
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/paraview
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/paraview/attachments/20170913/f63ca384/attachment.html>