vtkMultiBlockMergeFilter usage

Hi everyone,

I’m brand new in the world of Programmable Filter. In my python script, I’m trying to merge the blocks of a Multi-block Dataset (and then some additionnal steps that are already working). With the GUI, I simply use the Merge Blocks filter.

I’ve tried the following:

input0 = inputs[0]
print(intput0) # -> paraview.vtk.numpy_interface.dataset_adapter.CompositeDataSet

if input0.IsA("vtkCompositeDataSet"):    
    from paraview.vtk.vtkFiltersGeneral import vtkMultiBlockMergeFilter
    from vtk.numpy_interface import dataset_adapter as dsa
    mbmf = vtkMultiBlockMergeFilter()
    merged = dsa.WrapDataObject(mbmf.GetOutput())

    print(merged) # -> vtk.numpy_interface.dataset_adapter.CompositeDataSet

but it seems that the merged object is still a CompositeDataSet (while I’m expecting something like an UnstructuredGrid). In the CXX doxygen I see a merge method but I don’t know how to use it (if needed).

Any help is welcome!

Merge Blocks uses vtkDataObjectTreeToPointSetFilter, which is not a VTK filter but comes with ParaView:

from paraview.modules.vtkPVVTKExtensionsMisc import vtkDataObjectTreeToPointSetFilter


However your line lead to ImportError: cannot import name 'vtkDataObjectTreeToPointSetFilter' from 'paraview.modules.vtkPVVTKExtensionsMisc' with ParaView-5.9.0-RC4-MPI-Linux-Python3.8-64bit.

But following your lead, I found a vtkMergeBlocks in paraview.modules.vtkPVVTKExtensionsMisc that did the job. I ended up with:

input0 = inputs[0]

if input0.IsA("vtkCompositeDataSet"):
    from paraview.modules.vtkPVVTKExtensionsMisc import vtkMergeBlocks
    from vtk.numpy_interface import dataset_adapter as dsa
    mergeFilter = vtkMergeBlocks()
    input0 = dsa.WrapDataObject(mergeFilter.GetOutput())

Is it possible to find the paraview.*.vtk??? class/module corresponding to a given filter in the GUI?

In the Python shell, GetActiveSource().GetVTKClassName() gives you the class name. You can then locate its VTK module by searching the ParaView source code.

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