Re: Wighted Sum of TTrees

From: Venkatesh Kaushik <venkat.kaushik_at_cern.ch>
Date: Thu, 8 Jul 2010 18:13:16 +0200


Hi,
I usually have an eventweight branch with the weight, but when doing the analysis, mostly I make histogram of the variable(s) from each TTree appropriately weighting them before adding the histograms.
Cheers,
Venkat

On 7/8/10 6:08 PM, Axel Naumann wrote:
> Hi Hovhannes,
>
> you could simply create a new TTree with a weight branch and for further
> analysis add it as a friend to the merged tree. You fill that new tree
> for each event with the current tree's weight. Sounds like a major
> overhead - but because ROOT's TFiles are zipped this will leave you with
> almost nothing on disk and a very flexible layout in memory.
>
> Cheers, Axel.
>
> Hovhannes Khandanyan wrote on 07/08/2010 12:55 PM:
>
>> Dear ROOTers,
>>
>> I need to combine TTrees (presumably in TChain ) assigning weights to
>> each in much the same way as one makes a weighted sum of the TH1
>> histograms. What would be he easiest/recommended way to do this.
>>
>> Thanks,
>> Hovhannes
>>
>>
>>
>>
>
Received on Thu Jul 08 2010 - 18:13:21 CEST

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