Colin, The following few lines are extracted from the TH1 documentation at http://root.cern.ch/root/html/TH1.html *-* Convention for numbering bins *-* ============================= *-* For all histogram types: nbins, xlow, xup *-* bin = 0; underflow bin *-* bin = 1; first bin with low-edge xlow INCLUDED *-* bin = nbins; last bin with upper-edge xup EXCLUDED *-* bin = nbins+1; overflow bin *-* In the case of 2-d and 3-d histograms (and consistent with 1-d histograms) you can do : int globalbin = h->GetBin(binx,biny) ; // for a 2-d int globalbin = h->GetBin(binx,biny,binz); // for a 3-d In case of 1-d int globalbin = h->GetBin(binx) = binx You can then access the bin contents, errors, etc with h->GetBinContent(globalbin); globalbin is a linearized bin number in one-dim structure. Rene Brun C. Bernet wrote: > > Hi, > > It looks like when you create a 2d histogram hist, bins in x and y start > at 1. > When you execute the following command : > > hist->GetBin(1,1) > > the result is not 1 (0 would also be ok) but 19 in my case (TH2F, 16*16 > bins). > > Yet : > hist->GetBin(0,0) gives 0. But if you try to fill this bin > (hist->SetBinContent(0,1.)) and draw the TH2F, you see that this bin is > out of range.... > > Does anybody know if it's a bug or if the previous bins are used for > something else ? > > Thanks a lot. > Colin
This archive was generated by hypermail 2b29 : Tue Jan 04 2000 - 00:43:44 MET