Reading an ascii file and making an ntuple
{
// example of macro to read data from an ascii file and
// create a root file with an histogram and an ntuple.
gROOT->Reset();
FILE *fp = fopen("/user/brun/root/basic.dat","r");
Float_t x,y,z;
Int_t ncols;
Int_t nlines = 0;
TFile *f = new TFile("basic.root","RECREATE");
TH1F *h1 = new TH1F("h1","x distribution",100,-4,4);
TNtuple *ntuple = new TNtuple("ntuple","data from ascii file","x:y:z");
while (1) {
ncols = fscanf(fp,"%f %f %f",&x, &y, &z);
if (ncols < 0) 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);
fclose(fp);
f->Write();
}
ROOT page - Class index - Top of the page
This page has been automatically generated. If you have any comments or suggestions about the page layout send a mail to ROOT support, or contact the developers with any questions or problems regarding ROOT.