Putting objects in a root file [newbie]

From: Roger Mason <rmason_at_esd.mun.ca>
Date: Tue, 27 Sep 2005 12:33:40 -0230

Hello,

I created the following macro:

{
// Macro to read column data from an ascii file (wavenumber, shift,
// signal), do some fitting and save to a root file.
// Modified from tutorials/basic.C in the root distro.
   

   gROOT->Reset();
#include "Riostream.h"

   ifstream in;
// we assume a file file1.dat in the current directory
// this file has 3 columns of float data

   in.open("file1.dat");

   const Int_t nlines = 1850;
   Float_t wn[nlines],shift[nlines],signal[nlines];    TNtuple *ntuple = new TNtuple("ntuple","data from ascii file","wn:shift:signal");

   for (Int_t i = 0; i < nlines; i++) {

      in >> wn[i] >> shift[i] >> signal[i];
      if (!in.good()) break;
      if (i < 5) printf("x=%8f, y=%8f, z=%8f\n",wn[i],shift[i],signal[i]);
      ntuple->Fill(wn[i],shift[i],signal[i]);
      // Debugging
      //      if (i >= 100) break;

   }
   printf(" found %d points\n",i);
   in.close();

// Plot the graph

   cSp = new TCanvas("cSp","Spectrum",200,10,700,500);    cSp->SetFillColor(42);
   cSp->SetGrid();

   TGraph *gr = new TGraph(i,wn,signal);

   gr->SetLineColor(2);
   gr->SetLineWidth(1);
   gr->SetMarkerColor(4);
   gr->SetMarkerSize(0.2);
   gr->SetMarkerStyle(21);
   gr->SetTitle("File1.dat (050617)");
   gr->GetXaxis()->SetTitle("Wavenumber");
   gr->GetYaxis()->SetTitle("Signal");
   gr->Draw("AP");

   // TCanvas::Update() draws the frame, after which one can change it

   cSp->Update();
   cSp->GetFrame()->SetFillColor(21);
   cSp->GetFrame()->SetBorderSize(12);
   cSp->Modified();

g1 = new TF1("m1","gaus",13400,18200);

g2 = new TF1("m2","gaus",18200,18600);
total = new TF1("mstotal","gaus(0)+gaus(3)",13400,18600); Double_t par[9];

gr->Fit(g1,"R");
gr->Fit(g2,"R+");
g1->GetParameters(&par[0]);
g2->GetParameters(&par[3]);

total->SetParameters(par);
gr->Fit(total,"R+");

   TFile f("MySpectrum.root","RECREATE");

   f->Write();
   f.Close();
}

When I run it the plots are made and displayed and fit information appears on the canvas.

If I then exit root, start a new session:

root [0] TFile f("MySpectrum.root")
TFile f("MySpectrum.root")
root [1] .ls
.ls

TFile**		MySpectrum.root	
 TFile*		MySpectrum.root	

Should not .ls list the objects in the file?

If it matters, I'm using Version 5.02/00.

What am I doing wrong?

Roger Mason Received on Tue Sep 27 2005 - 17:12:32 MEST