# Groups of cells in unstructured grid

**URL:** <https://discourse.vtk.org/t/groups-of-cells-in-unstructured-grid/6532>\
**Category:** Development\
**Created:** [September 2, 2021, 3:15pm UTC](https://discourse.vtk.org/t/groups-of-cells-in-unstructured-grid/6532 "2021-09-02T15:15:59Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Sagues](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/a88e4f/32.png) [@Sagues](https://discourse.vtk.org/u/Sagues)\
**Post date:** [September 2, 2021, 3:15pm UTC](https://discourse.vtk.org/t/groups-of-cells-in-unstructured-grid/6532/1 "2021-09-02T15:15:59Z")

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I have to write vtk files using vtk library to write unstructured grids. And I need to create groups of cells according to type of cells (triangles, linees, etc) or materials (beams, shells, iron, etc…). Moreover, I would like to define properties to theses groups as name, colour and I would like identify these groups in paraview with these properties.

Which clases I should use? Dataset? FieldData? vtkMaterial? Filters?

Thanks very much