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| == ParaView3's python programmable filter. ==
| | This page moved [http://www.paraview.org/Wiki/Python_Programmable_Filter here]. |
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| The python programmable filter is a general purpose filter that the end user can program within the paraview GUI to manipulate datasets as needed. To use the filter, turn the PARAVIEW_ENABLE_PYTHON_FILTER cmake option on. This causes the make process to wrap paraview's classes into python callable format. The wrapping process is identical to that for the PARAVIEW_EMBED_PYTHON option and the two share the same sets of libraries at run time.
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| The filter is a wrapper around VTK's vtkProgrammableFilter class and adds to it:
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| * a string containing the user's script for the filter to execute
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| * an instance of the python interpreter with the wrapped paraview libraries imported
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| * the ability to easily change the output dataset type.
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| When the user selects "PythonScript" from the Filters menu, an empty programmable filter is created. The default behavior of the empty script is create a dataset if the same type as its input and to copy through the input dataset's structure. The GUI provides a selection menu where the user can choose from the five primary vtk dataset types for the output. The GUI also provides a text entry area where the user can type, edit or paste in a python script.
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| The following figure shows a python script that modifies the geometry of its input dataset.
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| [[Image:PyScriptFig1.jpg]] | |
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| #reads a poly data and modifies the geometry
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| pdi = self.GetPolyDataInput()
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| pdo = self.GetPolyDataOutput()
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| newPts = paraview.vtkPoints()
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| numPts = pdi.GetNumberOfPoints()
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| for i in range(0, numPts):
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| coord = pdi.GetPoint(i)
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| x,y,z = coord[:3]
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| x = x * 2
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| y = y * 0.5
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| z = 1
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| newPts.InsertPoint(i, x,y,z)
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| pdo.SetPoints(newPts)
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| The following figure shows a python script that produces an image data output with one cell per point in its input polygonal dataset.
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| [[Image:PyScriptFig2.jpg]]
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| #this example creates an Nx1x1 imagedata output
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| #and populates its cells with the point centered
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| #scalars of the input dataset
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|
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| #get a hold of the input
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| pdi = self.GetInput()
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| numPts = pdi.GetNumberOfPoints()
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|
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| #create the output dataset with one cell per point
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| ido = self.GetOutput()
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| ido.SetDimensions(numPts+1,2,2)
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| ido.SetOrigin(-1,-1,-1)
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| ido.SetSpacing(.1,.1,.1)
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| ido.SetWholeExtent(0,numPts,0,1,0,1)
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| ido.AllocateScalars()
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|
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| #choose an input point data array to copy
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| ivals = pdi.GetPointData().GetScalars()
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| ca = paraview.vtkFloatArray()
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| ca.SetName(ivals.GetName())
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| ca.SetNumberOfComponents(1)
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| ca.SetNumberOfTuples(numPts)
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| #add the new array to the output
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| ido.GetCellData().AddArray(ca)
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|
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| #copy the values over element by element
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| for i in range(0, numPts):
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| ca.SetValue(i, ivals.GetValue(i))
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