Re: AddFriend

Hi again,

I'm sorry , now is working

you have below how is the final script

Thank you ,

Henso

void Compare2trees(void){

  TFile *f0 = new TFile("ntuple0.root");   TTree *tree0 = (TTree*)f0->Get("Tree");

  TFile *f1 = new TFile("ntuple1.root");   TTree *tree1 = (TTree*)f1->Get("Tree");

  tree->AddFriend(tree1,"tree1");

  tree->Draw("ph_pt-tree1.ph_pt");

}

Henso Abreu wrote:
> Dear Rene,
>
> I did you say , but I had the following message:
>
> Processing Compare2trees.C...
> Error in <TTreeFormula::Compile>: Bad numerical expression :
> "tree0.ph_pt"
>
>
> Rene Brun wrote:
>> See the doc of TTree::AddFriend functionS.
>> To add a friend tree having the same name "tree" as in your case, do
>>
>> void Compare2trees(void){
>>
>> TFile *f0 = new TFile("ntuple0.root");
>> TTree *tree0 = (TTree*)f0->Get("Tree");
>>
>> TFile *f1 = new TFile("ntuple1.root");
>> TTree *tree1 = (TTree*)f1->Get("Tree");
>>
>> tree->AddFriend(tree1,"tree1");
>>
>>
>> tree->Draw("tree.ph_pt-tree1.ph_pt");
>>
>> }
>>
>> Rene Brun
>>
>> Henso Abreu wrote:
>>> Dear Rene,
>>>
>>> I did what you recommend to me, but I did not have success.
>>>
>>> I send you my code and also I remember you that my variable ph_pt is
>>> a vector.
>>>
>>> Thank you into advance,
>>>
>>> Henso
>>>
>>> void Compare2trees(void){
>>>
>>> TFile *f0 = new TFile("ntuple0.root");
>>> TTree *tree0 = (TTree*)f0->Get("Tree");
>>>
>>> TFile *f1 = new TFile("ntuple1.root");
>>> TTree *tree1 = (TTree*)f1->Get("Tree");
>>>
>>> tree0->AddFriend("tree1");
>>>
>>>
>>> tree0->Draw("tree0->ph_pt-tree1->ph_pt");
>>>
>>> }
>>>
>>>
>>> Rene Brun wrote:
>>>> see documentation of TTree::AddFriend. You can specify the treename
>>>> in TTree::Draw, eg
>>>> // tree.AddFriend("ft1","friendfile1.root");
>>>> // tree.AddFriend("ft2","friendfile2.root");
>>>> // tree.Draw("var:ft1.v1:ft2.v2");
>>>> // tree.Draw("var:ft1.var:ft2.var")
>>>>
>>>> When your Trees have the same name, specify an alias using the
>>>> special AddFriend function
>>>> TFriendElement* TTree::AddFriend(TTree* tree, const char* alias,
>>>> Bool_t warn)
>>>>
>>>>
>>>> Rene Brun
>>>>
>>>> Marc Escalier wrote:
>>>>> Dear roottalkers,
>>>>>
>>>>> I have a question from Henso, who is not yet subscribed to this forum
>>>>>
>>>>> Let's suppose we have two trees (tree0 and tree1) which have a
>>>>> same given variable name inside : "myvariable"
>>>>>
>>>>> how to do something like
>>>>>
>>>>> tree0->Draw("myvariable_from_tree0 - myvariable_from_tree1")
>>>>>
>>>>> and how to do something like :
>>>>>
>>>>> mydifference = tree0->GetValueOf n-th event of
>>>>> myvariable_from_tree0 - myvariable_from_tree0"
>>>>>
>>>>> AddFriend would be useful if the two tree would have different
>>>>> name of variables, but here, the variables have the same names
>>>>>
>>>>> (where myvariable is the same name in the two trees)
>>>>>
>>>>> thanks in advance for Henso
>>>>>
>>>>> ================
>>>>>>>>> TFile *f0 = new TFile("f0.root");
>>>>>>>>> TTree *tree0 = (TTree*)f0->Get("tree");
>>>>>>>>> TFile *f1 = new TFile("f1.root");
>>>>>>>>> TTree *tree1 = (TTree*)f1->Get("tree");
>>>>>>>>>
>>>>>>>>> // get variable pt of tree0 and keep it in float pt0
>>>>>>>>> // get variable pt of tree0 and keep it in float pt1
>>>>>>>>> //we wish :
>>>>>>>>> // pt0 - pt1 .
>>>>>>>>>
>>>>>>>>> }
>>>>>
>>>>
>>>
>>
>
Received on Mon Jan 25 2010 - 13:59:54 CET