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basic2.C
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1/// \file
2/// \ingroup tutorial_tree
3/// \notebook -js
4/// Create can ntuple reading data from an ascii file.
5/// This macro is a variant of basic.C
6///
7/// \macro_image
8/// \macro_code
9///
10/// \author Rene Brun
11
12void basic2() {
13 TString dir = gROOT->GetTutorialDir();
14 dir.Append("/tree/");
15 dir.ReplaceAll("/./","/");
16
17 TFile *f = new TFile("basic2.root","RECREATE");
18 TH1F *h1 = new TH1F("h1","x distribution",100,-4,4);
19 TTree *T = new TTree("ntuple","data from ascii file");
20 Long64_t nlines = T->ReadFile(Form("%sbasic.dat",dir.Data()),"x:y:z");
21 printf(" found %lld points\n",nlines);
22 T->Draw("x","z>2");
23 T->Write();
24}
#define f(i)
Definition: RSha256.hxx:104
long long Long64_t
Definition: RtypesCore.h:80
#define gROOT
Definition: TROOT.h:404
char * Form(const char *fmt,...)
Formats a string in a circular formatting buffer.
Definition: TString.cxx:2452
A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format.
Definition: TFile.h:54
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:574
Basic string class.
Definition: TString.h:136
const char * Data() const
Definition: TString.h:369
TString & ReplaceAll(const TString &s1, const TString &s2)
Definition: TString.h:692
TString & Append(const char *cs)
Definition: TString.h:564
A TTree represents a columnar dataset.
Definition: TTree.h:79
TH1F * h1
Definition: legend1.C:5
double T(double x)
Definition: ChebyshevPol.h:34