Hi,
If I understood it correctly; you want to chain 4 root files, say
file1.root, file2.root, file3.root, and file4.root, then you want to
produce a code using the MakeClass Functionality.
If this is the case, one possibility is:
At the directory where all these root files are located do:
root[] TChain ch("SMT");
root[] ch.Add("file*.root");
root[] SMT->MakeClass("myClass");
Assuming the root files are of same tree structure, the above lines should
result to the creatioin of myClass.C and myClass.h.
Then you can edit/modify the files according the nature of your
application.
I you want to understand the meaning of the codes and functions in the
TChain class I suggest you go to the site:
http://root.cern.ch/root/html/TChain.html
Hope it helps...keep trying.
On Sun, 17 Aug 2003, Justace Clutter wrote:
> I am a very new root user and have been trying to understand how the TChain
> works. There is a TTree, called SMT, spread out among four different root
> files. If I load the first file up using just a straight TFile I can access
> the data directly like the following:
>
> Int_t fdisk01_wedge01_n[768];
>
> SMT->SetBranchAddress("fdisk01_wedge01_n", &fdisk01_wedge01_n);
> SMT->GetEntry(0);
>
> However when I try to load all the data at once with TChain I get very
> confused.
>
> TChain *data_chain = new TChain("SMT");
>
> data_chain->Add("file1");
> data_chain->Add("file2");
> data_chain->Add("file3");
> data_chain->Add("file4");
>
> At this point I can not just run the same code as I did above. Now I ran the
> makeclass utilities and generated the class files, but now I am even more
> confused. The variables are declared in the class but only a few are set
> through the SetBranchAddress functions. But they are all available somehow.
>
> I know that this post is very confusing, but I am confused. I have went
> through the ROOT Users Guide and the examples but they did not help my
> understanding of this. Any help on this matter would be greatly appreciated.
> I guess that I just want to know how it works, I could just use the makeclass
> and close my eyes but that does not put a smile on my face.
>
> Justace Clutter
>
--
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Zaldy A. Nawang
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Japan
e-mail: zaldy@neutrino.kek.jp
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