[Rivet] Advice for unusual truth analysis

[Robert King]

Hi,

Thanks for that suggestion. I have already edited an analysis myself so I
can probably workout how to add a text file output, and then write a python
script that will parse the output of this into some sensible comparison.

Cheers

Robert

On 30 May 2011 18:01, Daniel Weyh <weyh at physik.hu-berlin.de> wrote:

> Hi Robert,
>
> I'd guess it will not be possible "on the fly".
> Rivet takes a single HepMC-Event, analyzes it and fills histograms with the
> result.
> For what you want to do, you need to load two events from two different
> sources (I guess Sherpa cannot serve you alternatingly with MPI on/off and
> the same random seed for two consecutive events)...
>
> The solution I have in mind - if you really need event-to-event comparison
> - is a bit dirty (I think) but should work:
> 1. In your Rivet analysis create a file-stream as member of your analysis
> (during init). (Remember to close in finalize() ;-) )
> 2. Do your analysis. During analyze append the number in question to your
> file (filestream << num_of_jets << endl;)
> 3. Run Sherpa another time with same random seed (I guess you know how to
> or check the Sherpa man), output as in 2. but in another file.
> 4. Analyze the two text files line by line externally. (<-- question to the
> others: are there python classes in Rivet which make creating an .aida by
> hand painless - to use Rivets plot facilities later on?)
> Or: Change 3 to read from the file created in 2 and store the differences
> in a histogram.
> As always depending on your needs.
> (How often you need it, automated or manually, how many observables (if not
> only #jets)...)
>
> The files shouldn't be to big. I guess order(10^6) runs = 10^6 lines *
> (1byte (newline)+10byte (precision fp)) ~ order(10 MB).
>
> This procedure requires you to write an analysis on your own (or at least
> to change the one you would have used for single-run).
> I hope this is not a problem for you - otherwise don't hesitate to ask.
>
>
> Good luck,
> Daniel
>
>
> Am 30.05.2011 um 17:54 schrieb Robert King:
>
> > Dear Rivet Experts,
> >
> > I have a slightly unusual truth level analysis and I hope you can advise
> me as to whether it is possible in Rivet. I have a limited experience with
> Rivet and it's not clear to me how one would/could do this.
> >
> > I would like to generate identical Sherpa samples (i.e. use the same
> random number seeds) one with MPI on and another with it off. I would then
> like to compare event by event the number of jets each event.
> > Is it possible to do this event by event comparison in Rivet?
> >
> > Many thanks for you advice
> >
> > Robert
> > _______________________________________________
> > Rivet mailing list
> > Rivet at projects.hepforge.org
> > http://www.hepforge.org/lists/listinfo/rivet
>
>
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