Hi again,
Ok, I see my english is worse than I thought.
What you proposed me to do is, if I well understood, to replace existing
histograms that already exist (overwrite).
This is not what I want to do. I may be confused you using the verb
"update". When I said "update an histogram" and didn't mean I wanted to
overwrite them, I want to "update"="increment" the number of entries.
Let me give you a short description of the procedure I want to use :
//--- first step I define a root file and some histograms
TFile f("Results.root");
TH1F hist("h","h",100,-2,2);
//-- then I loop on several data files (ROOT Tree)
while (nextDataFile()) {
//--- I load the ROOT data file
TFile * f2 = TFile::Open(CurrentDataFile);
TTree * tree = (TTree *) f2->Get("Global");
//--- I analyze each data files with a class created with
//--- a MakeClass applied on one of the data files
Analyze ana(tree);
//-- then I loop on events and give my histogram in input
//--- in order to fill it and "update"/"increment" it
ana.Loop(hist);
}
//--- then I write the histo in the file and close it
f->Write();
f->Close()
Other example : Imagine I want to plot the number of jets in one Run.
This Run is composed by 10 files, I want my histos to keep memory and just
increment data file from data file.
This doesn't work, my histogram is not updated ! I don't understand why !
I tried to use the Write() method inside the Loop() but it creates me
several cycles of my histos.
Do I miss something ?
I tried to do that another way, and I prefer this way because it allows to
stay more object oriented (better for C++ analysis)
This way work but create cycles of the same histo, and I would have to
merge them after, but I'm pretty sure you have a magical trick here
to cure that.
In this preocedure The main loop looks like that :
//-- then I loop on several data files (ROOT Tree)
while (nextDataFile()) {
//--- I load the ROOT data file
TFile * f2 = TFile::Open(CurrentDataFile);
TTree * tree = (TTree *) f2->Get("Global");
//--- I analyze each data files with a class created with
//--- a MakeClass applied on one of the data files
Analyze ana(tree);
//-- then I loop on events and give my histogram in input
//--- in order to fill it and "update"/"increment" it
ana.Loop();
}
I don't declare the histogram out of the loop.
In my analysis class, I have a pointer to an object of type MyHistoMgr (a
class of mine).
This hstogram manager has a data member which is the histogram I want to
fill. More exactly, the data member is a TH1F* .
In the Analyze::Loop() method, I initialize the pointer to the histogram
manager (out of the loop on event) :
during this initialization, I open "Results.root" (the output file
with my histogram), then I check if this file is empty (just check if
there are already the histogram I want) => if the file is empty, I create
histograms, if not, I initialize the pointer from the histogram manager
to the TH1F which has been previously defined.
Then I fill this histos event by event, and write to Results.root and
close the file.
And I follow this procedure data files after data files.
This works but create several cycles of the same histogram.
Is there a way to fill an histogram, write it into a root file, then close
the file, open it again, add entries to the histograms, write it to the
file, then close the file again .. and so on and so on without having
several cycles of the histogram ?
Please, if you need more explanation, I can try again to explain you
what I want, so don't hesitate and tell me if I gave bad explanation ..
many thanks for the help,
take care,
frederic.
On Sat, 1 Jun 2002, Rene Brun wrote:
> Hi Frederic,
>
> Suppose the following session:
> TFile f("junk.root","recreate");
> TH1F h("h","h",100,-2,2);
> h.Write();
> h.Fill(1);
> h.Write("",TObject::kOverwrite)
> f.ls(); //this will produce
> TFile** junk.root
> TFile* junk.root
> OBJ: TH1F h h : 0
> KEY: TH1F h;1 h
>
> As you can see, using the kOverwite flag will force a replacement
> of the previous object with the same name.
>
> Rene Brun
>
> On Wed, 29 May 2002, Frederic Villeneuve-Seguier wrote:
>
> >
> > Hi,
> > I probably gave bad explanation of what I want to do :
> > I run on several data files. On each data files I apply a class that
> > open/update a root files with some histograms.
> > In order to update histograms, I check if they are defined, if not I
> > create them, but if they are already define I declare pointers to them.
> >
> > This is working but in the root files where I store my histograms,
> > I have duplicated histos (different cycles of the same histos)
> >
> > Is there a way to avoid duplication, and to update an histogram ?
> >
> > thanks,
> > frederic.
> >
> >
> >
> > On Wed, 29 May 2002, Rene Brun wrote:
> >
> > > Hi Frederic,
> > >
> > > You must write the histograms to the file once you have filled them.
> > > In your case, add the statement
> > > f->Write();
> > > just after the loop filling your histograms
> > >
> > > Rene Brun
> > >
> > >
> > > On Tue, 28 May 2002, Frederic Villeneuve-Seguier wrote:
> > >
> > > >
> > > >
> > > > Hi all,
> > > >
> > > >
> > > > I want to study a large number of root files and I can't chain them.
> > > > So I study files one by one.
> > > > FOr somme coding reason, I need to apply a class inherited from a
> > > > MakeClass() on each of the files.
> > > > What I'm trying to do is :
> > > > I open in the "update" mode, the file where I store the results of my
> > > > studies. Then I declare (if it's the first time) or I "point at"
> > > > the histograms and fill/update them.
> > > > I use this in a C++ standalone mode.
> > > >
> > > > At the moment the file with the results is empty, and it seems that
> > > > the histograms aren't detected. I coded it this way :
> > > >
> > > > //--- Check if histos exists
> > > > TFile * f = TFile::Open("TriggStudies.root");
> > > > f->ls();
> > > > TH1F * check = NULL;
> > > > check = (TH1F * ) f->Get("sJ_nev_mu");
> > > > cout << "check = " << check << endl;
> > > > if (check == NULL) {
> > > > //--- Histograms Creation
> > > > cout << "| [#] Create Histograms for Trigger Studies" << endl;
> > > > diJets_Nevts_mu = new TH1F("sJ_nev_mu","N evt vs Pt of Jet - L1 mu",75,0,150);
> > > > } else {
> > > > diJets_Nevts_mu = (TH1F * ) f->Get("sJ_nev_mu");
> > > > }
> > > >
> > > > the problem I have is that data files after data files, the "check"
> > > > pointer is everytime empty.
> > > >
> > > > Does someone has an idea on what could be the source of this problem ?
> > > >
> > > > In an other way of saying that, Is it possible to fill histograms in a
> > > > root file, close it, then reopen this file, update the histograms
> > > > and re-close it again, and so on ... ?
> > > >
> > > >
> > > > many thanks,
> > > > take care,
> > > > frederic.
> > > >
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