# How to Show/Render a vtkMultiBlockDataset with the Paraview Python wrapper

**URL:** https://discourse.paraview.org/t/how-to-show-render-a-vtkmultiblockdataset-with-the-paraview-python-wrapper/8968
**Category:** ParaView Support
**Created:** [February 14, 2022, 3:21pm UTC](https://discourse.paraview.org/t/how-to-show-render-a-vtkmultiblockdataset-with-the-paraview-python-wrapper/8968 "2022-02-14T15:21:01Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![joaomlap](https://discourse.paraview.org/user_avatar/discourse.paraview.org/joaomlap/32/6609_2.png) [@joaomlap](https://discourse.paraview.org/u/joaomlap)
#### Post date: [February 14, 2022, 3:21pm UTC](https://discourse.paraview.org/t/how-to-show-render-a-vtkmultiblockdataset-with-the-paraview-python-wrapper/8968/1 "2022-02-14T15:21:01Z")

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Hi,

I am trying to use `paraview.simple` to render a vtkMultiBlockDataset.  
If I try to do:

`paraview.simple.Show(multiblock)`

I get the following error:  
`RuntimeError: Cannot show a sink i.e. algorithm with no output.`

I understand I need to wrap the vtkMultiBlockDataset in some kind of wrapper but I can’t find any documentation on how to do this. Can anyone help me understand how to make this work and where to find this information?

Thank you very much.

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### Author: ![pavel](https://discourse.paraview.org/user_avatar/discourse.paraview.org/pavel/32/8287_2.png) [@pavel](https://discourse.paraview.org/u/pavel)
#### Post date: [February 14, 2022, 5:55pm UTC](https://discourse.paraview.org/t/how-to-show-render-a-vtkmultiblockdataset-with-the-paraview-python-wrapper/8968/2 "2022-02-14T17:55:51Z")

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Hi,

In case the object of vtkMultiBlockDataSet has a name ‘multiblock’, the following code works for me:

```auto
mb = paraview.simple.FindSource('multiblock')
paraview.simple.Show(mb)
paraview.simple.Render()

```

Best Regards,  
Pavel

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<div class="post-metadata">

### Author: ![joaomlap](https://discourse.paraview.org/user_avatar/discourse.paraview.org/joaomlap/32/6609_2.png) [@joaomlap](https://discourse.paraview.org/u/joaomlap)
#### Post date: [February 14, 2022, 7:19pm UTC](https://discourse.paraview.org/t/how-to-show-render-a-vtkmultiblockdataset-with-the-paraview-python-wrapper/8968/3 "2022-02-14T19:19:34Z")

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Hi Pavel, thank you or your reply.

I am using pvpython to run my script. I have a HDF5 file for which we have a library that converts it to a vtkMultiBlockDataset.

So I currently have this VTK version:

```auto
mb = read_hdf5(file) # mb is of type vtkMultiBlockDataset
mapper = vtk.vtkCompositePolyDataMapper2()
mapper.SetInputDataObject(mb)
cdda = mapper.GetCompositeDataDisplayAttributes()
mapper.SetCompositeDataDisplayAttributes(cdda)

if not mapper.GetScalarVisibility():
    mapper.SetColorModeToMapScalars()
    mapper.ScalarVisibilityOn()

mapper.SelectColorArray("PressureCoefficient")
mapper.SetScalarModeToUsePointFieldData()
mapper.InterpolateScalarsBeforeMappingOn()

renderer = vtk.vtkRenderer()
renderWindow = vtk.vtkRenderWindow()
renderWindow.AddRenderer(renderer)

renderWindowInteractor = vtk.vtkRenderWindowInteractor()
renderWindowInteractor.SetRenderWindow(renderWindow)
renderWindowInteractor
    .GetInteractorStyle()
    .SetCurrentStyleToTrackballCamera()

actor = vtk.vtkActor()
actor.SetMapper(mapper)

renderer.AddActor(actor)
renderer.ResetCamera()
renderWindow.Render()

```

I am looking to replace this with a Paraview version where I use `paraview.simple` but I don’t know how to add the `mb` vtkMultiBlockDataset to the Paraview pipeline.

Thank you very much.