# How to write groups of cells in unstructured grid

**URL:** https://discourse.vtk.org/t/how-to-write-groups-of-cells-in-unstructured-grid/6565
**Category:** Support
**Created:** [September 6, 2021, 5:02pm UTC](https://discourse.vtk.org/t/how-to-write-groups-of-cells-in-unstructured-grid/6565 "2021-09-06T17:02:53Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### 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 6, 2021, 5:02pm UTC](https://discourse.vtk.org/t/how-to-write-groups-of-cells-in-unstructured-grid/6565/1 "2021-09-06T17:02:53Z")

</div>

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.