Combine VPP's?

[jessecarterMOOSE]

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Question

Is it possible to combine VPP's into one? I have multiple VPP's that sample values at qp's, so they each output element id, qp id, prop 1, prop 2, etc... The trick is that a) the number of number of VPP's needed by user is problem-dependent, and b) length of some of the VPP's is problem-dependent. My goal is to have a single VPP output csv file containing all qp data requested by user. Otherwise user has to merge csv files manually, which isn't difficult with pandas, but still an extra step that I would like to avoid. Values being sampled are - rank two mat props, vector mat props, and aux vars. I have a seperate VPP object for each category. I'm hoping for a solution that takes in existing VPP objects rather than combining all the object code into one big class, but I'll take what I can get.

[GiudGiud]

Hello

So I need to drive that residual down by another 5 orders of magnitude?

Do they have the same number of columns?
I imagine not. I imagine you have some element samplers and some Qp samplers.

Is it possible to combine VPP's into one?

No not currently. Not nicely at least. Technically most of the work in reading CSV files is in a utility so making a new object that reads multiple CSV files and merging them would not be too hard. But that's not exactly what you want.

[GiudGiud]

Waiting for Zach to pitch in on Reporter.

But otherwise the way to do it is to pass the names of the VPPs that will contribute, get the names of the vectors they declare probably going through the Reporter interface, get the types of these vectors, hopefully from the Reporter interface too, then call getVPPValue (or a similar name) and combine.

The declaration of the new combined vectors might need to be done in the constructor too, might require dependency resolution if we dont have it already

[zachmprince]

I think a VPP or reporter would work for this. A VPP solution would probably involve copying data, though. A Reporter could declare values as a pointer to the existing VPP, but would need to modify the CSV output class to support this kind of value. Another solution if all we care about is output is to add an option in the CSV output to combine vectors from specified VPPs into a single file. Personally, I think this last solution might be the best since we won't be copying data around and doesn't require pointer type conversions.

[jessecarterMOOSE]

@zachmprince @GiudGiud can you walk me through how I should do this?

[GiudGiud]

I would have started like this

But otherwise the way to do it is to pass the names of the VPPs that will contribute (in a vector parameter)
 get the names of the vectors they declare going through either the VPP or the Reporter-Interface, get the
types of these vectors, hopefully from the Reporter interface too (or might just be Real if all VPPs), then
call getVPPValue (or a similar name) and combine.

The declaration of the new combined vectors might need to be done in the constructor too, might require
dependency resolution if we dont have it already

but one must try to do it to find the difficulties

[GiudGiud]

@jessecarterMOOSE I'll take a look at this