[Rivet] adding histograms

[David Grellscheid]

Hi Frank,

have you kept that up-to-date? David Winn found that he had to modify 
the copy you gave him quite a bit to work with 1.5.0. I don't have any 
other details, though, it may well relate something that he messed up 
originally.

   David



Frank Siegert wrote:
> 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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