2D Scatter plot in log scale does not work?

ROOT
1

Hi All,

I’m trying to get a scatter plot using a tree. I have made a plot in linear scale and seems to be OK (Canvas c1).
Later, I have created a new canvas, set log-log and the plot makes no sense!! What am I doing wrong?
I have tried both with and without the last line (c2->Update()) not to avail.

Thanks in advance for your help.
Pablo

BTW: I’m using 3.10/02 in Linux RH 9.0

The script follows

{gROOT->Reset();
// This file has two Trees named ‘mr’ and ‘dn’. I’m interested in
// variables HVEM and LVEM

TFile *CSU_Duets_V3 = TFile::Open(“CSU_Duets_V3.0_0312.root”);

TCanvas *c1 = new TCanvas(“c1”,“linear”,1,1,400,400);
mr->SetMarkerStyle(20);
c1->DrawFrame(1,1,2000,2000);
mr->Draw(“LVEM:HVEM”,"",“same”);

TCanvas *c2 = new TCanvas(“c2”,“log”,1,500,400,400);
c2->DrawFrame(1,1,2000,2000);
c2->SetLogx();
c2->SetLogy();
mr->Draw(“LVEM:HVEM”,"",“same”);
//c2->Update();
}
CSU_Duets_031229_0312.root (63.2 KB)

2

Hi Pablo,

For some reason (not yet completly clear to me) the following way works:

{
   gROOT->Reset();
   // This file has two Trees named 'mr' and 'dn'. I'm interested in
   // variables HVEM and LVEM

   TFile *CSU_Duets_V3 = TFile::Open("CSU_Duets_031229_0312.root");

   TCanvas *c1 = new TCanvas("c1","linear",1,1,400,400);
   mr->SetMarkerStyle(20);
   c1->DrawFrame(1,1,2000,2000);
   mr->Draw("LVEM:HVEM","","same");

   TCanvas *c2 = new TCanvas("c2","log",1,500,400,400);
   c2->DrawFrame(1,1,2000,2000);
   mr->Draw("LVEM:HVEM","","same");   
   c2->SetLogx();
   c2->SetLogy();
}

ie, set the log scales after the TTree drawing

3

Thanks for reporting this problem with your combination of calls.
It is now fixed in the CVS version.
The fix will be included in the binary files for version 4.00/04 this week.

Rene

4

Thanks for the idea!
I’ll get the new version as soon as is available.