# GenerateCompositeDataSetFromHierarchy in Python

**URL:** https://discourse.paraview.org/t/generatecompositedatasetfromhierarchy-in-python/10110
**Category:** Development
**Created:** [August 5, 2022, 10:43pm UTC](https://discourse.paraview.org/t/generatecompositedatasetfromhierarchy-in-python/10110 "2022-08-05T22:43:05Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![HollowSun0](https://discourse.paraview.org/user_avatar/discourse.paraview.org/hollowsun0/32/431_2.png) [@HollowSun0](https://discourse.paraview.org/u/HollowSun0)
#### Post date: [August 5, 2022, 10:43pm UTC](https://discourse.paraview.org/t/generatecompositedatasetfromhierarchy-in-python/10110/1 "2022-08-05T22:43:05Z")

</div>

Hi everyone!

Quick question… How does one call the method…

```auto
output = vtkDataAssemblyUtilities.GenerateCompositeDataSetFromHierarchy(
        outPDSC, outPDSC.GetDataAssembly())

```

? I keep getting this error:

`ValueError: cannot create object of unknown type "vtkSmartPointer_I19vtkCompositeDataSetE"`