Hi Vuko, With version 3.02/07 (or newer 3.03) you can specify the number of bins in the generated histogram (eg: t1->Draw("temp:time >> temphist(500,0,500,600,-300,300)",""); I would suggest to use a TProfile histogram instead of a 2-d histogram for this kind of plot t1->Draw("temp:time >> temphist","","profs"); On your last point, the function is GetNbinsX (not GetNBinsX Rene Brun On Mon, 4 Mar 2002, Vuko Brigljevic wrote: > Hi Rene, > > Sorry for the delay in my reaction, I had to turn to something > else urgently to finish Moriond results. > > Rene Brun wrote: > > > > Hi Vuko, > > > > The Hist.Binning.nD.x variables were only introduced in version 3.02/07 ! > > Ah, ok. Well, I eventually realized that we got that version > installed at SLAC, even if the official BABAR software still > uses 2.*, but I can use 3.02/07 for my work so that solves > that problem :) > > > I do not understand what you mean by a "binning too raw". > > Could you tell me the min/max/binwidth of the produced histogram > > and the values you were expecting instead ? > > Well, what I mean is that the histogram "temphist" coming out > of the lines: > > t1->Draw("temp:time >> temphist",""); > temphist->GetXaxis()->SetTimeDisplay(1); > temphist->Draw(); > > has very few bins, ~40, in each dimension, and that is not enough > for the plot I want to make. But since 2 pictures explain better > than 1000 words, here you see: > > 1) output of the t1->Draw(): > > http://www.slac.stanford.edu/~vuko/pictures/Tree-draw.gif > > 2) output of the temphist->Draw(): > > http://www.slac.stanford.edu/~vuko/pictures/TH2F-draw.gif > > (WARNING for the archive: these links will probably removed after March > 2002!) > > BTW, I tried to call GetNBinsX() for the histogram and got > an error (see below), but that must just be my beginner ignorance > in basic ROOT concepts. > > I repeat: version 3.02/07 solves my problem. > > Thanks, > > Vuko > > > root [1] temphist->GetNBinsX() > Error: Can't call TH2F::GetNBinsX() in current scope > FILE:/var/tmp/baaTUaOvf_cint LINE:1 > Possible candidates are... > filename line:size busy function type and name (in TH2F) > filename line:size busy function type and name (in TH1F) > filename line:size busy function type and name (in TH1) > filename line:size busy function type and name (in TNamed) > filename line:size busy function type and name (in TObject) > filename line:size busy function type and name (in TAttLine) > filename line:size busy function type and name (in TAttFill) > filename line:size busy function type and name (in TAttMarker) > filename line:size busy function type and name (in TArrayF) > filename line:size busy function type and name (in TArray) > filename line:size busy function type and name (in TH2) > *** Interpreter error recovered *** > root [2] > > > ======================================================================== > Vuko Brigljevic | Mail : SLAC, Mail Stop 41 > Lawrence Livermore National Laboratory | P.O. Box 4349, Stanford > Nuclear and Particle Physics Division | CA 94309, USA > | SLAC-Office : B280- room 143 > Member of the BaBar Collaboration | Phone : +1-650-926 8512 > <vuko@slac.stanford.edu> <http://www.slac.stanford.edu/~vuko> > ======================================================================== > > > > > > Rene Brun > > > > Vuko Brigljevic wrote: > > > > > > Hi root friends, > > > > > > still the first steps of a new rooter... > > > > > > What I am trying to do: fill a 2D histogram > > > (some variable vs time) from a tree, change the > > > X-axis to represent time, and redraw: > > > > > > t1->Draw("temp:time >> temphist",""); > > > temphist->GetXaxis()->SetTimeDisplay(1); > > > temphist->Draw(); > > > > > > Problem: > > > I am loosing completely the precision of the first > > > plot (from the TTree::Draw()) in the histogram. > > > The binning must be too raw and the binning and > > > the entries must be drawn randomly > > > second histogram is so raw that the structure > > > of the plot completely disappears. > > > > > > What I tried: > > > 1) I read in the root manual about the environment > > > variables: > > > > > > Hist.Binning.2D.x: 500 > > > Hist.Binning.2D.y: 500 > > > Hist.Binning.2D.Prof: 10000 > > > > > > I added these lines to my ~/.rootrc (the values > > > are mine, not the default), and checked that > > > they have been correctly read: > > > > > > root [0] gEnv->Print() > > > Hist.Binning.2D.x: 500 [User] > > > Hist.Binning.2D.y: 500 [User] > > > Hist.Binning.2D.Prof: 10000 [User] > > > > > > Still I have the same problem > > > > > > 2) I tried to predefine the histogram with a > > > higher binning: > > > TH2F * temphist=new TH2F("h2", "test", 1500, > > > initTime, endTime, 500, 10., 20.); > > > t1->Draw("temp:time >> temphist",""); > > > temphist->GetXaxis()->SetTimeDisplay(1); > > > temphist->Draw(); > > > > > > but this time the plot from the 2nd Draw() is empty. > > > > > > Any idea? > > > > > > In case it matters, I am running Root Version 2.23, > > > a bit old I know, but it's still the BABAR standard > > > > > > Thanks, > > > > > > Vuko > > > > > > ======================================================================== > > > Vuko Brigljevic | Mail : SLAC, Mail Stop 41 > > > Lawrence Livermore National Laboratory | P.O. Box 4349, Stanford > > > Nuclear and Particle Physics Division | CA 94309, USA > > > | SLAC-Office : B280- room 143 > > > Member of the BaBar Collaboration | Phone : +1-650-926 8512 > > > <vuko@slac.stanford.edu> <http://www.slac.stanford.edu/~vuko> > > > ======================================================================== > > -- >
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