[ROOT] Ntuple projection.

From: Zhou SuiJian (zhousj@ihep.ac.cn)
Date: Sun Jun 06 2004 - 15:11:51 MEST


Dear All,
  Can anybody help me to solve the problem?
I want to project two of the variables in a
Ntuple into a TH2F, which has a predefined
range for both X and Y axises. When I do 
the following:

TH2F *ha2 =new TH2F("ha2","ADC",200,-100.,100.,200,-100.,100.);
TFile f1("tmp_proton.root");
TNtuple *n1=(TNtuple*)f1.Get("h9");
n1->Draw("Y:X>>ha2","","scat");

 The scatter plot is drawn but it does not fit the 
ranges I predifined(-100. to 100.).

And when I do:
  ha2->Draw("scat");
It shows 0 entries and of course draw nothing!
May be I missed something?

  Thanks!
  zhou



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