[Paraview] Need help with programmable filter output

[Sean Ziegeler]

Scott,
The following code will create a field variable:

output.ShallowCopy(inputs[0].VTKObject)  # Include this if you haven't 
already
value = vtk.vtkFloatArray()
value.SetName('varname')
value.SetNumberOfComponents(1)
value.InsertNextValue(42)
output.GetFieldData().AddArray(value)

Obviously, you'll want to set 'varname' to a meaningful variable name 
and "42" to some usable value (e.g., Theta).

Now, I would have thought that the Plot Global Variables Over Time 
filter would do the trick, but it appears (if I'm reading the 
documentation correctly), that the field data actually needs to be an 
array with the same number of elements as there are time steps.  You'd 
have to tweak the code above to do this, and I guess, play through all 
the time steps to construct it.

Unless someone has another idea?

-Sean


On 12/06/12 11:08, Scott Ripplinger wrote:
> Okay, I've done a little more work on this and the following is what I
> have so far:
>
> import math
>
>
> r = inputs[0].PointData['d']/2
>
> SurfArea = math.pi*r*r
>
>
> z = inputs[0].Points[:,2]
>
> h = 0.00015 - abs(z - 0.00015) - r
>
> H0 = h/r
>
>
> numPoints = inputs[0].GetNumberOfPoints()
>
> SurfCvg = 0
>
> for i in range(numPoints):
>
>    if H0[i] < 0.002:
>
>      SurfCvg = SurfCvg + SurfArea[i]
>
>
> Theta = SurfCvg/(0.010*0.001*2)
>
>
> output.RowData.append(Theta, 'Theta')
>
>
> The output is set to vtkTable.  When I try running this, though, I get
> the following error message repeated three times:
>
>
> ERROR: In ..\..\..\..\src\VTK\Filtering\vtkDemandDrivenPipeline.cxx,
> line 827
>
> vtkPVDataRepresentationPipeline (000000001444A130): Input for connection
> index 0 on input port index 0 for algorithm
> vtkGeometryRepresentation(000000001279BFE0) is of type vtkTable, but a
> vtkDataSet is required.
>
>
> Do I need to manually define my SurfCvg and SurfArea variables as
> vtkTable types?  I'm just a bit lost at this point, but feeling closer.
>
>
> -Scott
>
>
>
>
> On Fri, Nov 30, 2012 at 10:18 AM, Berk Geveci <berk.geveci at kitware.com
> <mailto:berk.geveci at kitware.com>> wrote:
>
>     Output should be vtkTable. By the way, if you have numpy installed,
>     this could be done much more efficiently and in less code. See
>
>     http://paraview.org/Wiki/ParaView/Users_Guide/Python_Programmable_Filter
>     http://paraview.org/Wiki/ParaView/Users_Guide/Python_Calculator
>
>     You may also want to check the numpy documentation.
>
>     In general, if your data is medium to large, you want to avoid for
>     loops over all cells/points in Python.
>
>     Best,
>     -berk
>
>
>     On Thu, Nov 29, 2012 at 11:35 PM, Scott Ripplinger
>     <bigbluedart at gmail.com <mailto:bigbluedart at gmail.com>> wrote:
>
>         I am attempting to run an analysis on some data which requires
>         summing up some numbers down to a single value for the whole
>         domain for each time step.  I'm having trouble figuring out how
>         to get the output and what VTK classes and functions to use.
>           Here is what I have so far:
>
>         import math
>
>         input = self.GetInputDataObject(0,0)
>
>         output = self.GetOutputDataObject(0)
>
>         numPoints = input.GetNumberOfPoints()
>
>         points = input.GetPointData()
>
>         SurfCvg = 0
>
>         for i in xrange(numPoints):
>
>           d = points.GetArray('d').GetValue(i)
>
>           coords = input.GetPoint(i)
>
>           z = coords[2]
>
>           h = 0.00015 - abs(z - 0.00015) - 0.5*d
>
>           H0 = 2*h/d
>
>           if (H0 < 0.002):
>
>            SurfCvg = SurfCvg + 0.25*math.pi*d*d
>
>         Theta = SurfCvg/(0.01*0.001)
>
>         outputarray = vtk.vtkFloatArray()
>
>         outputarray.SetNumberOfValues(1)
>
>         outputarray.SetValue(0, Theta)
>
>         output.GetRowData().AddArray(outputarray)
>
>
>         I'm not even sure what to use as the output data set type.  In
>         the end I need to plot (or export as a table) the value of
>         "Theta" across all my time steps.  Any guidance would be
>         appreciated.
>
>
>         -Scott
>
>
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