Getting 1D histos from 2D histo

[giaccaria]

Hi,
I know that a TProfile can give me information such as mean and RMS for each x-bin of a 2D histogram,
but is there a quick way to print the actual histogram of the events in each bin ?

Cheers,
Giacomo

[giaccaria]

I’ve found the answer to my question in this post:

Making slices for TH2F

Hi, I have a TH2F, and I want to make Y projections for the different X bins. I can do this by issuing commands like, h2->ProjectionY(“bin1”,Xbin1,Xbin1), h2->ProjectionY(“bin2”,Xbin2,Xbin2), etc. but is there a method which I can invoke at the command line and make all the projection in one shot. We have FitSlicesY, which fits the Y slices, but no method which just makes them. vivek

[giaccaria]

I have another question related to this topic.

I see that FitSlicesY has the option:

“N” means do not show the result of the fit

but it’s not clear to me where the fit result should be shown when I don’t choose this option (I’d like to see the histogram and its fit for each x bin)

[Tomaskom]

Normally, the fitted function is attached to the histogram you’re fitting, so when it is drawn, the function is drawn with it. When you use the “N” option, this is not done - useful when you want to get the fit values, but not the visual representation.

This is based on the TH1::Fit() documentation, but I expect the fit slices (which generates a list of histograms) to follow the same logic. See root.cern.ch/doc/master/classTH … 3ca47dabdd

[giaccaria]

Right, but I don’t get the fitted histogram as output anywhere when I remove the “N” option, so I’m wondering where they should appear.

[couet]

Right, but I don’t get the fitted histogram as output anywhere when I remove the “N” option, so I’m wondering where they should appear.

Can you post a simple macro reproducing your problem ?