[Rivet] adding histograms

[Frank Siegert]

Hi Robert,

I have a script which takes multiple .aida files and merges (averages) 
them into one. This is a good enough approximation if your aida files 
contain roughly the same number of events. Is that what you are after?

Cheers,
Frank

On 18/03/11 09:19, Robert King wrote:
> Ok, Thanks for letting me know Andy. I'll just write a pyroot script to
> do it myself then...
>
> On 17 March 2011 23:13, Andy Buckley <andy.buckley at ed.ac.uk
> <mailto:andy.buckley at ed.ac.uk>> wrote:
>
>     On 17/03/11 08:40, Robert King wrote:
>      > Hi Rivet Experts,
>      >
>      > I expect this is a simple question, but I couldn't see how to do
>     it. I
>      > want to generate a large MC sample and create histograms using Rivet.
>      > I do this by splitting the job up into 100 sub jobs. I then want to
>      > add the histograms that are made for each subjob into one
>     histogram. I
>      > suppose I could convert the .adia files to root files and add
>     together
>      > in root but I hoped there might be a method in Rivet already for
>     doing
>      > this...
>
>     Hi Robert,
>
>     Unfortunately this can't be done "properly" at the moment, because the
>     output histograms are just x, y, and error values rather than containing
>     the sort of weighted moments information that's needed to do a proper
>     statistical combination. If you convert them to ROOT you'll get TGraphs,
>     which are the same sort of deal, or TH1Fs in which case the combination
>     is going to be a bit dodgy.
>
>     This has been a bit of a thorn in our side for a while, but it was more
>     important to keep developing the physics content than to rewrite the
>     histogramming. That's changing with our next release: we're taking a
>     couple of months to migrate all the histogramming to a new system which
>     will support all these good things. But for now it's approximations, I'm
>     afraid: sorry!
>
>     Andy
>
>     --
>     Dr Andy Buckley
>     SUPA Advanced Research Fellow
>     Particle Physics Experiment Group, University of Edinburgh
>
>     The University of Edinburgh is a charitable body, registered in
>     Scotland, with registration number SC005336.
>
>
>
>
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