Hi Pascal,
Could you make clear what is your problem?
Provide a simple macro that does not work.
In your example below, you have an extremely dangerous construct with
the statement;
DSDEDT->Add(..)
Where is DSDEDT defined?
Also, remember that when you create an histogram, this histogram is
automatically added to the list of objects in memory associated to teh
current file.
Rene Brun
Pascal Girard wrote:
>
> Hi Rooters,
>
>
> I switch to the 2.20 version , and this might have been part of the
> problem,
> However I'm still not able to obtain the Histogram resulting from the
> projection.
> Nevertheless I thing this problem rather come from the directory where
> the Histogram is set than
> the Draw() object itself :
>
> I'm openning a succesion of files where the a TNtuple has been filled
> for each run.
>
>
> TFile *InNT;
> char file[15];
> for (int i=11400;i<11900;i++) {
> sprintf(file,"HistoRun.%d",i);
> if ( !((TUnixSystem*)gSystem)->AccessPathName(file) ) {
> cout<<"Opening "<<file<<endl;
> InNT = new TFile (file,"read");
> ProjNT(InNT);
> InNT->Close();
>
>
> and then I'm projection this TNtuple into the TH1F,
> My guess would be that the TH1F stays in the directory associated with
> the NTtuple it comes from.
> (even with the "+" in ->Draw("MSMass>>+DSDEDT"....) )
> To bypass this problem, I've been obliged to declare a new TH1F
> "current" to project the TNtuple
> and then to copy "current" into a "repository" TH1F :
>
>
>
> void PiAna::ProjNT(TFile* TF){
>
> TH1F* current = new TH1F("current","tmp",120,-0.1,0.6);
> TNtuple *FromFile;
> TF->cd(); //optional
> FromFile = (TNtuple*) TF->Get("Neutral_Events");
> FromFile->Draw("MSMass>>current",cut,"goff");
> DSDEDT->Add(DSDEDT,current);
> current->Delete();
>
> return;
> }
>
> This works, I obtain the same result than interactively but is king of
> "heavy"
>
> thanks for your concerne
>
> Pascal
>
>
> > Pascal,
> > I cannot reproduce this problem. I assume you are using 2.20 or higher.
> >
> > Always use TTree::Draw. Project is an interface to Draw.
> >
> > I tested your example interactively and in batch mode without
> > problems.
> >
> > Rene Brun
> >
> > Pascal Girard wrote:
> > >
> > > Hi all,
> > >
> > > I'm trying to project a TNtuple in to a pre-define
> > > TH1F from a c++ code.
> > > I Have seen on roottalk some references to this issue,
> > > but It seems it doesn't work for me :
> > >
> > > I define a TH1F* RES :
> > >
> > > TH1F* RES;
> > > RES = new TH1F("DEDT",title,120,-0.1,0.6);
> > >
> > > ...
> > >
> > > I read a TNtuple from file :
> > >
> > > TNtuple *FromFile;
> > > FromFile = (TNtuple*) TF->Get("Neutral_Events");
> > > FromFile->Project("DEDT","MSMass",cut,"goff");
> > >
> > > ...
> > >
> > > when I visualize DEDT , it's empty.
> > >
> > > I tryed the Draw solution :
> > >
> > > > TH1F *h1 = new TH1F(..
> > > >
> > > > The TTree::Draw function (in the form "m>>+h1") fills an histogram
> > > > with the name "h1". In your case h1 is the name of the pointer,
> > > > not the name of the histogram ("blat").
> > > > It is a good practice to have the pointer_name = histogram_name.
> > > > Your program will work with:
> > > > TH1F *h1 = new TH1F("blat", "quat", 20, 4.5, 6);
> > > > ntuple->Draw("m>>+blat", "(4.5 > h1->Draw();
> > > > or
> > > > TH1F *blat = new TH1F("blat", "quat", 20, 4.5, 6);
> > > > ntuple->Draw("m>>+blat", "(4.5 > blat->Draw();
> > > >
> > > > Rene Brun
> > >
> > > But It doesn't recognise the "goff" option and try to open a canvas from a
> > > batch job. And the final result is an empty histogram.
> > >
> > > In interactive root (on HP), Project(...) doesn't seems to work,
> > > however
> > > the Draw solution does.
> > >
> > > Any suggestions ?
> > >
> > > thanks
> > >
> > > Pascal
> > >
> > >
> > >
> >
> >
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