Hi Sebastian, Your example should work without having to draw anything before hand. (I would need to know more about your trees and Sel.GetTitle() to be able to investigate more). Note that a TEventList only keep information about the entry number and the cut and do NOT keep any information about the tree it self. Thus your strategy would yield a TEventList that is only valid for one tree at a time (i.e. it is not cumulative). If you are looking for a cumulative TEventList, you may want to consider building a TChain of the trees in your array and running Draw only once on the chain. Cheers, Philippe. -----Original Message----- From: owner-roottalk@pcroot.cern.ch [mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Sebastian Boeser Sent: Tuesday, February 19, 2002 8:13 AM To: RootTalk Subject: [ROOT] Drawing in a TEventList Hello ROOTs, i tried to generate TEventLists using TTree:Draw() on an array of TTrees (Trees[]) for (int ds = min; ds < max; ds++){ //Reseting Tree-EventList Trees[ds]->SetEventList(0); // Draw into list cout << ((TTree*)Trees[ds])->Draw(">> list",Sel.GetTitle()); // Get the list TEventList * list = (TEventList*)gDirectory->Get("list"); cout << "\t " << list->GetN() << " Events\n"; } As this would only work if i did a TTree::Draw() in a histogram before, i tried to circumvent this by accesing the TTreePlayer // Print the events in a list TEventList * list = new TEventList("list",Sel.GetTitle()); list->SetDirectory(0); //Lets play with this tree TTreePlayer * tPlay = ((TTree*)Trees[ds])->GetPlayer(); //Assign selection to tree tPlay->CompileVariables("",Sel.GetTitle()); //Now run the TreePlayer loop (5 means assign to elist) tPlay->EntryLoop(5,list); Unfortunatley this would not work either. If i specify a variable in addition to the selection in TTreePlayer::CompileVariables I would just get the last event of the tree in the list, otherwise i got an empty list as before. Now my question is if there is a way to generate a TEventList from a Tree w/o drawing something from the Tree before ? Thanks Sebastian --------------------------------------------------- \|/ Sebastian Böser / ~~ @--OO Rinkartstr. 3 \ ? 12437 Berlin \ v Tel: 030 / 532 19 008 || sboeser@ph.tum.de
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