RE: Error in drawing a histogram from ntuple file

Replace

   Int_t Nentries = ntuple -> GetEntries(); with

   Long64_t Nentries = ntuple -> GetEntries(); Cheers,
Philippe
-----Original Message-----
From: owner-roottalk_at_pcroot.cern.ch [mailto:owner-roottalk_at_pcroot.cern.ch] On Behalf Of Raghunath Sahoo
Sent: Sunday, November 13, 2005 1:40 AM
To: roottalk_at_pcroot.cern.ch
Subject: [ROOT] Error in drawing a histogram from ntuple file

Dear All,

 I have a macro which reads a .root file which contains a ntuple.  While plotting, it draws a canvas but doesn't plot the desired  observable. The error message is:

root [0] .x test.C
Warning: conversion from 64bit to 32bit integer FILE:test.C LINE:13  Nentries = 169

          : Real Time = 1.01 seconds Cpu Time = 0.96 seconds root [1] .q

In line: 13, I have,

Int_t Nentries = ntuple -> GetEntries();

I am using root version 4.04/02 in Redhat linux 7.2 gcc: 2.96

I could plot the branches in the ntuple thru TBrowser(). And also, I could plot in root giving command lines.

Any help is highly appreciated.

Regards,
Raghunath.

NB: The macro is the following:

 void test()
{

gROOT->Reset();
gStyle->SetOptStat(0);
gBenchmark->Start("");
Float_t Et_had, Et_ptGT;

TFile *f = new TFile("correctionFactors_20154.root"); TNtuple *ntuple = (TNtuple*)f -> Get("ntuple"); TH1F *EtT_had = new TH1F("Et_had","Total hadronic Et",250,0.,500.);

Int_t Nentries = ntuple -> GetEntries(); cout << " Nentries = " << Nentries << endl;

ntuple -> SetBranchAddress("Et_had",&Et_had); ntuple -> SetBranchAddress("Et_ptGT",&Et_ptGT); for (Int_t i=0; i< Nentries; i++)
  {
    ntuple -> GetEntry(i);
    // cout <<Et_had <<endl;
    EtT_had -> Fill(Et_had);
  }
TCanvas *test = new TCanvas("test","",2);

EtT_had -> Draw();
f->Close();
gBenchmark->Show("");

}

• Raghunath Sahoo * Phone: +91-0674-2301172 *
• Doctoral Scholar * 2301058 *
• Institute Of Physics * Lab:- 230,H-303,359(Extn) *
• Sachivalaya Marg * Fax: +91-0674-2300142 *
• Bhubaneswar * URL: http://www.iopb.res.in/~raghu *
• Orissa (India)-751005 * email: raghu_at_iopb.res.in *

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• raghu_at_bnl.gov * raghu_at_mail.cern.ch *

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