# Usage of CellSize filter
**URL:** https://discourse.paraview.org/t/usage-of-cellsize-filter/8418
**Category:** ParaView Support
**Created:** [November 16, 2021, 3:47pm UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418 "2021-11-16T15:47:04Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@benediktB](https://discourse.paraview.org/u/benediktB)
#### Post date: [November 16, 2021, 3:47pm UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418/1 "2021-11-16T15:47:04Z")
Dear community,
I simulate bubble collapses.
With a pvbatch-script I want to calculate the volume of the bubble.
I use the precompiled version ParaView-5.10.0-RC1-osmesa-MPI-Linux-Python3.9-x86\_64
The following function should do this:
```auto
def Process( file ):
xdmf = pv.Xdmf3ReaderS( FileName = [file] )
xdmf.CellArrays = ['levelset']
bubble = createThreshold( xdmf )
v = computeCellSize( bubble )
i = np.sum(v)
print(i)
return i
```
The ´createThreshold´ function creates a dataset which contains only the bubble, therefore the name of its result. The `computeCellSize` function looks like this:
```auto
def computeCellSize( input_data ):
cs = pv.CellSize(registrationName='CellSize1', Input=input_data)
cs.ComputeVertexCount = 0
cs.ComputeLength = 0
cs.ComputeArea = 0
size = cs.CellData.GetArray('Volume')
return size
```
It returns the volume array to the `Process` function. However, the `i = np.sum(v)` line only returns `None` values.
What is the reason for this?
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 16, 2021, 3:52pm UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418/2 "2021-11-16T15:52:17Z")
UpdatePipeline ?
---
### Author:  [@benediktB](https://discourse.paraview.org/u/benediktB)
#### Post date: [November 16, 2021, 4:10pm UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418/3 "2021-11-16T16:10:09Z")
I added UpdatePipeline before the sum-line, but I keep getting `None`-values
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 16, 2021, 4:12pm UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418/4 "2021-11-16T16:12:01Z")
```auto
size = cs.CellData.GetArray('Volume')
```
This is wrong, you need to fetch the data from the server first.
---
### Author:  [@benediktB](https://discourse.paraview.org/u/benediktB)
#### Post date: [November 17, 2021, 9:47am UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418/5 "2021-11-17T09:47:31Z")
Could you tell me how I can do that?
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 17, 2021, 9:49am UTC](https://discourse.paraview.org/t/usage-of-cellsize-filter/8418/6 "2021-11-17T09:49:53Z")
Something like:
```auto
cs.ComputeArea = 0
cs.UpdatePipelline()
dataset = servermanager.Fetch(cs)
size = dataset.GetCellData().GetArray('Volume')
```