# Derive values for multiple cases simultaneously
**URL:** https://discourse.paraview.org/t/derive-values-for-multiple-cases-simultaneously/2244
**Category:** ParaView Support
**Created:** [July 18, 2019, 10:35am UTC](https://discourse.paraview.org/t/derive-values-for-multiple-cases-simultaneously/2244 "2019-07-18T10:35:19Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@papercace](https://discourse.paraview.org/u/papercace)
#### Post date: [July 18, 2019, 10:35am UTC](https://discourse.paraview.org/t/derive-values-for-multiple-cases-simultaneously/2244/1 "2019-07-18T10:35:19Z")
Hi,
I’ve got several cases open i Paraview of flow around a cylinder, but with different initial velocities in each case. I’m trying to calculate the drag on the cylinders. I know how to do it for one case, but how do I do it for all cases simultaneously such that I get all their drags in one single table?
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### Author:  [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [July 19, 2019, 2:13pm UTC](https://discourse.paraview.org/t/derive-values-for-multiple-cases-simultaneously/2244/2 "2019-07-19T14:13:50Z")
Welcome to ParaView, @papercace.
This might be tricky to do completely within the ParaView GUI. Instead, you may want to use Python scripting to do it. ParaView can record your actions in a Python “trace”, producing a script you can then edit to run your analysis in a loop over datasets. To create a Python trace, choose the Tools -\> Start Trace menu item. Do the actions that compute the drag on one cylinder. When you are done, choose Tools -\> End Trace. You’ll see the Python code needed to rerun the analysis you just performed. From that, you can grab the drag value, and then store it in a table that you can write to, say, a CSV file.
Hope that helps.