[vtkusers] Parallel coordinates Extraction

[David Doria]

On Fri, Mar 25, 2011 at 8:12 PM, Darshan Pai <darshanpai at gmail.com> wrote:
>
> This example
> http://www.vtk.org/Wiki/VTK/Examples/Python/Infovis/ParallelCoordinatesExtraction
> I can run it , but can someone please explain this part in the code
> rep.SetInputArrayToProcess(0,0,0,0,'RTDataGradient')
> rep.SetInputArrayToProcess(1,0,0,0,'RTData')
> rep.SetInputArrayToProcess(2,0,0,0,'Elevation')
> rep.SetInputArrayToProcess(3,0,0,0,'BrownianVectors')
>
> How is this data acquired ? I never used Infovis before so I am not clear what these lines are doing exactly
> Thanks in advance
> Darshan

The SetInputArrayToProcess function is among the most confusing ones I
have encountered (it doesn't have anything to do with vtkInfovis)

http://www.vtk.org/doc/nightly/html/classvtkAlgorithm.html#a6bea16e1329609dbccce0ff8d2367484

I believe all that is happening is the arrays RTDataGradient, RTData,
Elevation, BrownianVectors are being set as vertical axes in the
parallel coordinate representation. The first parameter, 'idx', is
setting the 0th array, the 1st array, etc. I just always put 0's for
the rest of the arguments.

It has always seemed to me that for saneness there should be a

void SetInputArrayToProcess (int idx, const char *name)

so the explanation of "I don't know, just put 0's" doesn't ever have to be used.

David