Int_t smpl(){
  ROOT::EnableImplicitMT();
  //ROOT::DisableImplicitMT();

  ofstream ofs;
  ofs.open("smpl.csv");
  ofs.setf(ios::fixed);

  ofs << "xval,yval" << endl;
  Double_t max =1E+5;
  for(Int_t i =0;i <max;i++){
    Double_t xv =(Double_t)i;
    Double_t yv =max -(Double_t)i;
    ofs << xv << "," << yv << endl;
  }
  ofs.close();

  auto csv_rdf =ROOT::RDF::FromCSV("smpl.csv");
  auto xval =csv_rdf.Take<Double_t>("xval");
  auto yval =csv_rdf.Take<Double_t>("yval");
  auto gr =new TGraph(xval->size(),&xval->at(0),&yval->at(0));
  gr->Draw("al");

  gPad->SetLogx();
  gPad->SetLogy();

  return 0;
}