Re: TChain

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Mar 05 1998 - 15:27:59 MET


Laurent,
In your example below, simply change the statement:
    nt->Draw("Krun");
to
    ch->Draw("Krun")
and your program will work correctly.


Rene Brun


Laurent Mirabito wrote:
> 
> Hello,
> 
> I have the following problem using TChain
> I created one TTree per run and I tried to Draw variable using TChain:
> 
> root [4] TChain ch("nt")
> root [5] ch.Add("Cluster20638.root")
> root [6] ch.Add("Cluster20637.root")
> root [7] ch.ls()
> OBJ: TChainElement      nt Cluster20638.root : 0
> OBJ: TChainElement      nt Cluster20637.root : 0
> root [8] nt->Print()
> Error: No symbol nt->Print() in current scope  FILE:/tmp/17867haa LINE:1
> root [9] nt->Draw("Krun")
> Error: No symbol nt->Draw("Krun") in current scope  FILE:/tmp/17867iaa
> LINE:1
> But when I open file by file it works
> root [0] TFile f("Cluster20638.root")
> root [1] f.ls()
> TFile**         Cluster20638.root
>  TFile*         Cluster20638.root
>   KEY: TTree    nt;1    An example of a ROOT tree
> root [2] nt->Print()
> ************************************************************************************
> *Tree    :nt        : An example of a ROOT
> tree                                    *
> *Entries :    17430 : Total  Size =    662542 bytes  File  Size =
> 208130 bytes *
> *        :          : Tree compression factor =
> 4.12                             *
> ************************************************************************************
> *Branch  :Krun      :
> Krun/I                                                       *
> *Entries :    17430 : Total  Size =     49994 bytes  File Size  =
> 230 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 217.37           *
> *..................................................................................*
> *Branch  :Kevt      :
> Kevt/I                                                       *
> *Entries :    17430 : Total  Size =     49994 bytes  File Size  =
> 17564 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 2.85           *
> *..................................................................................*
> *Branch  :Nclus     :
> Nclus/i                                                      *
> *Entries :    17430 : Total  Size =     49996 bytes  File Size  =
> 6198 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 8.07           *
> *..................................................................................*
> *Branch  :Idet      :
> Idet/i                                                       *
> *Entries :    17430 : Total  Size =     49994 bytes  File Size  =
> 3309 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 15.11           *
> *..................................................................................*
> *Branch  :Vclu      :
> Vclu/F                                                       *
> *Entries :    17430 : Total  Size =     49994 bytes  File Size  =
> 22553 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 2.22           *
> *..................................................................................*
> *Branch  :Noiclu    :
> Noiclu/F                                                     *
> *Entries :    17430 : Total  Size =     49998 bytes  File Size  =
> 18954 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 2.64           *
> *..................................................................................*
> *Branch  :Xclu      :
> Xclu/F                                                       *
> *Entries :    17430 : Total  Size =     49994 bytes  File Size  =
> 22081 bytes *
> *Baskets :        2 : Basket Size =     25000 bytes  Compression=
> 2.26
> 
> ...
> 
>         Any Ideas ?
>         Best regards
>         Laurent
> --
> Laurent Mirabito
> IPN Lyon



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