Hi everyone,
I’ve only recently started using root and I’m gradually learning the ropes.
I need to exract the actual data points from a 2-D histogram(not the number of entries,i.e getbin()).Meaning, I want the actual co-ordinates of the data ponts on the histogram. Is it possible to do that ? Any help would be welcome!
http://root.cern.ch/root/html/TH1.html#TH1:FindBin
http://root.cern.ch/root/html/TH1.html#TH1:GetBinContent
http://root.cern.ch/root/html/TH1.html#TH1:GetBinError
Thanks for the links Pepe. However, getbincontent simply returns the number of events in a bin, no? I needed the actual data points (coordinates of each of those events). Didn’t find any function to do that…is there any other way ?
For this you need the original data which were used for the histogram creation/filling.
Oh,ok. So the root file itslef isn’t enough?
I don’t know how you store the “original data”. They may reside in a root file, for example, in a TTree. I simply say that having the histogram is not enough for what you want to do now.
Histograms are binned data set. Once data are binned the value you can get about a bin are the bin lower edge, the bin upper edge and the bin content. You can also get associated errors if there some. Bute the actual X Y (z) coordinates fo the points are lost. That’s why Pepe suggested you to go back to original data which may reside in a TTree. Also you might be happy with the information coming from the histogram (those I mentioned).