TTree and TKey

From: Pierpaolo Righini <>
Date: Thu, 24 Feb 2005 18:02:32 +0100 (MET)

Dear Rooters,
using various version of ROOT I have always the following result: writing to an output file a tree, when its dimension become sufficiently big, it appears to be contained in the file under 2 different TKey. Is it normal?
Calling the file "myfile" I got with "myfile->ls()":

TFile**         data_2005-02-23.root
 TFile*         data_2005-02-23.root
  KEY: TTree    T;3     Tree containing user info
  KEY: TTree    T;2     Tree containing user info

or with "myfile->GetListOfKeys()->Print()": TKey Name = T, Title = Tree containing user info, Cycle = 3 TKey Name = T, Title = Tree containing user info, Cycle = 2

Note that the dimension of the file is about 40 Mb and that the tree as been constructed as follow (using some class User):

 TTree *T = new TTree("T","Tree containing user info");

 Int_t split = 99;
 Int_t bsize = 32000;
 User  *user = 0;
 TBranch *branch = T->Branch("user", "User", &user,
			       bsize, split);

 user = new User();


so if the dimension is small enough (the number of "user" is small in the tree) I have only 1 key otherwise I got 2 keys...

thanks a lot.

   Pierpaolo Righini Received on Thu Feb 24 2005 - 18:02:53 MET

This archive was generated by hypermail 2.2.0 : Tue Jan 02 2007 - 14:45:05 MET