[Paraview] [EXTERNAL] ParaView - Variables and different Time Steps

[Scott, W Alan]

Here is an answer from Cory last summer, off list, to one of my customers:  

On Tue, Jul 11, 2017 at 2:50 PM, Cory Quammen <cory.quammen at kitware.com> wrote:
> Dear <redacted>,
>
> I think the Force Time filter will come in handy here for this use 
> case. It can be used to "freeze" a dataset at a certain timestep.
>
> * Load can.ex2
> * Add a Force Time filter. Set the timestep to the one whose 
> displacement you want to be zero. The output of this filter is the
> can.ex2 dataset "frozen" at the chosen timestep. It will not change as 
> you advance through time.
> * Select both can.ex2 and the ForceTime1 sources in the Pipeline 
> Browser. Note that the original can.ex2 source will update as the 
> timestep changes, but the ForceTime1 source will not change.
> * Add a Python Calculator filter to subtract the displacement in the 
> "frozen" data set from the current timestep in can.ex2. Set the 
> expression to
>
> inputs[0].PointData['DISPL'] - inputs[1].PointData['DISPL']
>
> The order of inputs into the Python Calculator is not well defined, so 
> you may need to swap the indices in inputs[0] and inputs[1] to get the 
> correct sign on the result, but this should work.
> * Finally, add a Plot Selection over Time filter. This filter will run 
> over all time steps, subtracting the data from the current timestep 
> from the data in the "frozen" timestep produced by the Force Time 
> filter, and plot the result in a graph. The first timestep should have 
> a value of 0.
>
> Please let me know if this approach isn't clear or doesn't work.
>
> Best regards,
> Cory
>
>
> On Tue, Jul 11, 2017 at 1:27 PM, Scott, W Alan <wascott at sandia.gov> wrote:
>> Morning team,
>>
>> <redacted>, one of my customers, has been working on an issue for a while.  
>> Ken and Andy have replied, but I don’t think we understood, or 
>> answered, <redacted> problem.  Here is what he is trying to do, using can.exo as an example.
>>
>>
>>
>> I assume this will require the Programmable Filter – if so, mind 
>> voodooing up the source?
>>
>>
>>
>> I believe that <redacted> basically wants to be able to subtract two 
>> timesteps from each other.  I thought I had an example from a 
>> previous thread, but can’t find it.
>>
>>
>>
>> Thanks!
>>
>>
>>
>> Alan
>>
>>
>>
>>
>>
>>

> -----Original Message-----
> From: ParaView [mailto:paraview-bounces at paraview.org] On Behalf Of
> Carolin Helbig
> Sent: Wednesday, January 10, 2018 2:57 AM
> To: paraview at paraview.org
> Subject: [EXTERNAL] [Paraview] ParaView - Variables and different Time
> Steps
> 
> Dear ParaView team,
> 
> I read a post at the ParaView website concerning variables and different time
> steps (see https://public.kitware.com/pipermail/paraview/2014-
> May/031054.html). I have a similar problem and I want to access values from
> different time steps using the programmable filter with multiple inputs. I
> unfortunately have no idea how to access other time steps using the
> programmable filter. Could you give me some advice or a hint where I can
> find detailed information about that issue? I would be very happy if you
> could help me.
> 
> Best regards,
> Carolin.
> 
> --
> Dr. Carolin Helbig
> 
> Department Umweltinformatik
> Helmholtz-Zentrum für Umweltforschung GmbH - UFZ Permoserstraße 15 I
> 04318 Leipzig
> Tel.: +49 341 235 - 1032
> Email: carolin.helbig at ufz.de
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> 
> 
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