Hot wo Add a Leaf to an existing Tree?

ROOT
1

Hallo, im sure, there is an easy solution, i checked already the manual and didnt find it. i hope someone can halp me here!

i have an .root file. inside is a Tree that has 10 Branches. every Branch has about 100 integers.
i would like to add integers to this Branches. Here my code:
TreeExists is a bool, it just check, if the tree already exists;

if (!TreeExists)
{
Tree=new TTree(“T1”,“Tsample”);
}

else {
Tree = (TTree*)File->Get(“T1”);
}

    Tree->Branch("Time",&Ev.Time,"Time/I");  
    Tree->Branch("LumiBlock",&Ev.LumiBlock,"LumiBlock/I");  
    Tree->Branch("ID",&Ev.ID,"ID/I");  
    Tree->Branch("Item",&Ev.Item,"Item/I");
    
    Tree->Fill();

that code generates me a lot of Trees in my .roor File. I just want to keep me first created tree and fill the branches.

2

Create another Tree in the same file or (better) in a different file and declare the second Tree to be a friend of the original Tree. See TTree::AddFriend

Rene

3

ok, it works, but its not a good solution, because i have very huge files, and if i use that method, it copies all the files+new files to a new tree and rewrite the old one. i would like to keep the old one and just add the new leafs.
i tried it with TChain, but it will not work )-;

4

NOOOOOOOOOOOOOOOO!
It should not copy the old Tree. Read carefully my message.
The new Tree should contain only the new branches. The old Tree and old file remains untouched.

Rene

5

hmm, it doent work, kan u check my code?
here an example;

int a;
int b;
{
    TFile *File=new TFile("~/T1.root","recreate");
    TTree *Tree=new TTree("T1","Tsample");    
    Tree->Branch("a",&a,"a/I");
    Tree->Branch("b",&b,"b/I");
    
    for (int i=0; i<10; i++) {
        a=i;
        b=i*i;
        Tree->Fill();
    }
    File->Write();
    File->Close();
}


{
    TFile *FileF=new TFile("~/T1F.root","recreate");
    TTree *TreeF=new TTree("T1","Tsample");    
    TreeF->Branch("a",&a,"a/I");
    TreeF->Branch("b",&b,"b/I");
    
    for (int i=10; i<12; i++) {
        a=i;
        b=i*i;
        TreeF->Fill();
    }
    FileF->Write();
    FileF->Close();
}

TFile *t=new TFile("~/T1.root","open");
TFile *f=new TFile("~/T1F.root","open");

TTree *tree;
TTree *frie;
t->GetObject("T1", tree);
f->GetObject("T1", frie);

tree->AddFriend(frie);
tree->Scan();

and when i have the whole tree in my programm and i want to save it into a rootfile. it hast to copy every entry again?

6

…hallo?..

7

[quote]hmm, it doent work, kan u check my code?[/quote]How does it fail?

To make it easier to distinguish them you should call your new TTree and your new leaves with a different name. i.e.[code]int a;
int b;
{
TFile *File=new TFile("~/T1.root",“recreate”);
TTree *Tree=new TTree(“T1”,“Tsample”);
Tree->Branch(“a”,&a,“a/I”);
Tree->Branch(“b”,&b,“b/I”);

for (int i=0; i<10; i++) {
a=i;
b=i*i;
Tree->Fill();
}
File->Write();
File->Close();
}

{

TFile *FileF=new TFile("~/T1F.root",“recreate”);
TTree *TreeF=new TTree(“T1F”,“Additional Information”);
int c;
TreeF->Branch(“c”,&c,“c/I”);

for (int i=10; i<12; i++) {
c=iii;
TreeF->Fill();
}
FileF->Write();
FileF->Close();
}

TFile *t=new TFile("~/T1.root",“open”);
TFile *f=new TFile("~/T1F.root",“open”);

TTree *tree;
TTree *frie;
t->GetObject(“T1”, tree);
f->GetObject(“T1F”, frie);

tree->AddFriend(frie);[/code]

[quote]tree->Scan();
[/quote]If I remember correctly the default Scan does not traverse friends. But you can do:tree->Scan("a:b:c:T1F.c");

Cheers,
Philippe.