# Add Vector Cell Data in reader
**URL:** https://discourse.paraview.org/t/add-vector-cell-data-in-reader/7508
**Category:** ParaView Support
**Created:** [June 29, 2021, 10:50am UTC](https://discourse.paraview.org/t/add-vector-cell-data-in-reader/7508 "2021-06-29T10:50:45Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@David\_Cortes](https://discourse.paraview.org/u/David_Cortes)
#### Post date: [June 29, 2021, 10:50am UTC](https://discourse.paraview.org/t/add-vector-cell-data-in-reader/7508/1 "2021-06-29T10:50:45Z")
Hello, I’m trying to write a new reader using a library of mine called `oommfpy`. I have cell data in the form of vectors. When I write my VTK files I specify this data as `VECTORS m double`. How can I do this in the reader? This is the `RequestData` method I’m writing
```auto
def RequestData(self, request, inInfoVec, outInfoVec):
output = dsa.WrapDataObject(vtkRectilinearGrid.GetData(outInfoVec))
# Use oommfpy to read the mesh
if self._file_format == 'omf':
mesh = oommfpy.MagnetisationData(self._filename)
else:
mesh = oommfpy.FieldData(self._filename)
mesh.generate_coordinates()
mesh.generate_field()
output.SetDimensions(mesh.nx + 1, mesh.ny + 1, mesh.nz + 1)
output.SetXCoordinates(mesh.grid[0])
output.SetYCoordinates(mesh.grid[1])
output.SetZCoordinates(mesh.grid[2])
# Cell data
# This is a 3 * nx * ny * nz array. How to specify VECTORS?
output.CellData.append(mesh.field.reshape(-1), 'm')
```
---
### Author:  [@Kenichiro-Yoshimi](https://discourse.paraview.org/u/Kenichiro-Yoshimi)
#### Post date: [July 4, 2021, 3:07am UTC](https://discourse.paraview.org/t/add-vector-cell-data-in-reader/7508/2 "2021-07-04T03:07:57Z")
Hello,
I don’t know what the value of **mesh.field.shape** is, but adding vector data is often done as follows.
```python
import vtk
from vtk.numpy_interface import algorithms as algs
m = algs.make_vector(mesh.field[0],mesh.field[1],mesh.field[2])
output.CellData.append(m, 'm')
```