Read data from an ascii file and create a root file with an histogram and an ntuple. See a variant of this macro in basic2.C.
Author: Rene Brun
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, April 17, 2024 at 11:23 AM.
read file $ROOTSYS/tutorials/tree/basic.dat this file has 3 columns of float data
TString dir = gROOT->GetTutorialDir();
dir.Append("/tree/");
dir.ReplaceAll("/./","/");
ifstream in;
in.open(Form("%sbasic.dat",dir.Data()));
Float_t x,y,z;
Int_t nlines = 0;
auto f = TFile::Open("basic.root","RECREATE");
TH1F h1("h1","x distribution",100,-4,4);
TNtuple ntuple("ntuple","data from ascii file","x:y:z");
while (1) {
in >> x >> y >> z;
if (!in.good()) break;
if (nlines < 5) printf("x=%8f, y=%8f, z=%8f\n",x,y,z);
h1.Fill(x);
ntuple.Fill(x,y,z);
nlines++;
}
printf(" found %d points\n",nlines);
in.close();
f->Write();
x=-1.102279, y=-1.799389, z=4.452822 x=1.867178, y=-0.596622, z=3.842313 x=-0.524181, y=1.868521, z=3.766139 x=-0.380611, y=0.969128, z=1.084074 x=0.552454, y=-0.212309, z=0.350281 found 1000 points