Hi Luca, I have tried to reproduce your problem with the ntuple in hsimple.root (see ROOTSYS/tutorials). For me it works fine. My macro is: void tree() { TCanvas *c1 = new TCanvas("c1","Tree test"); c1->SetLogy(); TH2F *frame = new TH2F("frame","", 100, -3, 3, 100, 0.01, 3); frame->Draw(); TFile f("hsimple.root"); ntuple->Draw("py:px","py>0.1 && px>-3 && px <-1","same"); } Cheers, Olivier On Thu, 16 Dec 2004, Luca Grandi wrote: > Dear all, > > I found a strange behavior using tree Draw on a specific frame. > > When i plot a tree without a predefined frame and i change the Y axis scale > from linear to log the range is fixed by root and several points of the plot > are excluded. For this reason I have followed a suggestion to create a > predefined frame to fix the logarithmic range for the Y axis. > I am using the following example > > TCanvas *c7 = new TCanvas("c7","Lifetime",+0,+0,900,680); > c7->SetLogy(); > TH2F frame7("frame","Lifetime", 1, 0, 60, 1000, 1, 1000); > frame7.Draw(); > > Now with the treeviewer I plot on the frame a first plot with > > tv_tree->Draw("br.var1:br.var2","several cuts","same"); > > At this point everything is OK. > > When I want to add another plot (with a similar command) on the same frame > but with different cuts it creates a strange plot where the points are > placed in a way different from what they look like when I plot them > singularly. In other words the points are placed in a strange way and > filling some region of the plot that are wrong (I know this since when I > plot the second plot as first I found a regular behavior). > Suggestions? > > Regards > > Luca > > > -- Org: CERN - European Laboratory for Particle Physics. Mail: 1211 Geneve 23 - Switzerland Mailbox: J25910 E-Mail: Olivier.Couet@cern.ch Phone: +41 22 7676522 WWW: http://cern.ch/Olivier.Couet/ Fax: +41 22 7677155
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