Logo ROOT  
Reference Guide
 
Loading...
Searching...
No Matches
basic2.C
Go to the documentation of this file.
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:406
char * Form(const char *fmt,...)
Formats a string in a circular formatting buffer.
Definition TString.cxx:2489
A ROOT file is composed of a header, followed by consecutive data records (TKey instances) with a wel...
Definition TFile.h:53
1-D histogram with a float per channel (see TH1 documentation)
Definition TH1.h:621
Basic string class.
Definition TString.h:139
const char * Data() const
Definition TString.h:376
TString & ReplaceAll(const TString &s1, const TString &s2)
Definition TString.h:704
TString & Append(const char *cs)
Definition TString.h:572
A TTree represents a columnar dataset.
Definition TTree.h:79
TH1F * h1
Definition legend1.C:5
double T(double x)