[Rivet] 2D Histograms in Rivet

[Sercan Sen]

Hi all,

Attached 2D histograms are produced with Rivet 1.8.1. The first histogram is without any normalization. I run over ~1K events and fill the x and y for each event with the same value like below;

_hist_2D->fill ( myValue, myValue, weight );   ( the weight is 1 for each event and the bin sizes are 0.2 )

However, the color coding does not represent the number of events. As you know rivet normalize the histograms to the bin sizes by default. Therefore, what we see on the color scale is the values divided by binsize_x * binsize_y . It depends what you want to show but would be more meaningful if this 'by default' bin size normalization don't be applied for 2D histograms.

The second plot is produced by ROOT. I dump the histograms values in Rivet to a text file and read them by ROOT. In this case, color coding represent the actual number of events which is much simpler to read.

Third one is again with Rivet but after scaling the histogram with the size of the bins.  Then, we get the same as ROOT.

scale (_hist_2D, binSize*binSize);

Anyway. I've tried a few tricks to get rid of this blue background in Rivet 2D histograms, however, couldn't find an easy solution yet. Before digging the codes I would like to ask you, if there is any simple way to remove this blue background ?

( btw, it's easy to understand from the histogram but let me tell you that myValues are always > 0. and this blue region does not corresponds to the 0 on the color scale. )

Cheers,
Sercan


[cid:F933F95E-DDD8-4128-A04F-C075C8BF0D1B at cern.ch]
[cid:F9A18B42-4115-4CDC-B4BD-6C80AB6EA217 at cern.ch]
[cid:C73FE46C-AEC0-4179-97AB-7657BFF4CC85 at cern.ch]

--
Sercan Sen http://cern.ch/ssen
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