// needs hsimple.root

void makeList() {
   TFile *f1 = new TFile("hsimple.root");
   TTree *ntuple = (TTree*) f1->Get("ntuple");
   ntuple->Draw(">>elist","py>2");
   TEventList *elist = (TEventList*)gDirectory->Get("elist");
   TFile ef("elist.root","recreate");                       
   elist.Write();
}

void makeSmall() {
   TFile *f = new TFile("elist.root");
   TEventList *elist = (TEventList*)f->Get("elist");
   TFile *f1 = new TFile("hsimple.root");
   TTree *ntuple = (TTree*) f1->Get("ntuple");
   ntuple->SetEventList(elist);
   TFile *f2 = new TFile("small.root","recreate");
   TTree *small = ntuple->CopyTree("");
   small->Write();
   small->Print();
}