Hi Anton, If you use a TH2F to set the X,Y scale before drawing your TGraphs, you can find the zoom position of both axis with: int firstXbin =h->GetXaxis()->GetFirst(); int lastXbin =h->GetXaxis()->GetLast(); int firstYbin =h->GetYaxis()->GetFirst(); int lastYbin =h->GetYaxis()->GetLast(); then, get the corresponding coordinates with double xmin = h->GetXaxis()->GetBinLowEdge(firstXbin); double xmax = h->GetXaxis()->GetBinUpEdge(lastXbin); double ymin = h->GetYaxis()->GetBinLowEdge(firstYbin); double ymax = h->GetYaxis()->GetBinUpEdge(lastYbin); you can also do simply: double xmin = gPad->GetUxmin(); double xmax = gPad->GetUxmax(); double ymin = gPad->GetUymin(); double ymax = gPad->GetUymax(); Note that the maximum zoom precision depends on the number of bins allocated for each axis. Rene Brun KOSU_FOKIN@garbo.lucas.lu.se wrote: > > Hello Rene, > > assume I have a graph drawn on top of a TH2 histogram (as we usually do in > ROOT to draw multiple graphs on the same picture). Assume I zoom a histogram > along X axis. Now in my code I want to zoom the histogram along Y axis so > that zoomed (along X) portion of graph fits Y histogram range. To do so I have > to know Ymin and Ymax of my graph on the zoomed X. How can I get it? I have tried > TH2::GetMinimum() and TH2::GetMaximum() but they both return zero all the > time. > > Regards, > Anton
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