Unable to fill properly Histogram from TTree

[jenegger]

Hi experts,
I am trying to fill a histogram From a leaf of a TTree but it doesn’t work as it should. When trying to fill the Histogram in the interactive mode (just typing root -l and then typing the code to the terminal) it works well. I load my .root file and call the TTree and write
evt->Draw(“TofWHitData.fTime.fTime”)

But then I wanted to write a small code which I want to expand,as I want to make various fits. But there it doesn’t work. My code:

void scratch(){
        Double_t x;
        TFile* file = TFile::Open("data_s444_main0038.root");
        TTree* t1 = (TTree*)file->Get("evt");
        TH1D* h_raw_pos = new TH1D("h_raw_pos","SofToFWSingleTcalData.fRawTimeNs",10000,-10,10);
        t1->SetBranchAddress("SofToFWSingleTcalData.fRawTimeNs",&x);
        Int_t nentries = (Int_t)t1->GetEntries();
        for (Int_t i = 0; i<nentries;i++) {
                t1->GetEntry(i);
                h_raw_pos->Fill(x);
                }
        TCanvas* c2 = new TCanvas();
        h_raw_pos->Draw();
}

Here I get the following Histogram:

All the values are squeezed to 0.
I tried different ways to implement this code but I still don’t know why I can’t access the data of the leaf of the TTree properly. I have read something about MakeClass but I don’t know how that works and if it is the correct way…

Thanks in Advance
Tobias

[Wile_E_Coyote]

Attach the oputput from: t1->Print();

See also:

Header files for Trees

“Most recent” documentation about how to generate and use an “analysis skeleton”: TTree::MakeClass (see also “ROOT User’s Guide” → “Trees” → “Using TTree::MakeClass”) TTree::MakeSelector (see also “ROOT Primer” → “File I/O and Parallel Analysis” → “N-tuples in ROOT” → “For the advanced user: Processing trees with a selector script” and “ROOT User’s Guide” → “Trees” → “Using TTree::MakeSelector” and “ROOT User’s Guide” → “Example Analysis”) TTree::MakeProxy ROOT::RDataFrame (uses the T…

[jenegger]

Hi Wile_E_Coyote,
here the output form t1->Print();

******************************************************************************
*Tree    :evt       : /cbmout                                                *
*Entries :  2810612 : Total =      6686598088 bytes  File  Size =  581875660 *
*        :          : Tree compression factor =  11.50                       *
******************************************************************************
*Br    0 :EventHeader. : FairEventHeader cbmout.Event.EventHeader.           *
*Entries :  2810612 : Total  Size=  168664338 bytes  File Size  =    6085090 *
*Baskets :      257 : Basket Size=   17175531 bytes  Compression=  27.72     *
*............................................................................*
*Branch  :R3BEventHeader : cbmout.EventHeader.R3BEventHeader                      *
*Entries :  2810612 : BranchElement (see below)                              *
*............................................................................*
*Br    1 :R3BEventHeader : BASE cbmout.EventHeader.R3BEventHeader            *
*Entries :  2810612 : Total  Size=  174286858 bytes  File Size  =    6622059 *
*Baskets :      264 : Basket Size=   17175531 bytes  Compression=  26.32     *
*............................................................................*
*Br    2 :R3BEventHeader.fEventno :                                          *
*         | UInt_t cbmout.EventHeader.R3BEventHeader.fEventno                *
*Entries :  2810612 : Total  Size=   11247137 bytes  File Size  =    3916534 *
*Baskets :       39 : Basket Size=     673280 bytes  Compression=   2.87     *
*............................................................................*
*Br    3 :R3BEventHeader.fTrigger :                                          *
*         | UInt_t cbmout.EventHeader.R3BEventHeader.fTrigger                *
*Entries :  2810612 : Total  Size=   11247137 bytes  File Size  =      64551 *
*Baskets :       39 : Basket Size=     673280 bytes  Compression= 174.22     *
*............................................................................*
*Br    4 :R3BEventHeader.fTimeStamp :                                        *
*         | ULong_t cbmout.EventHeader.R3BEventHeader.fTimeStamp             *
*Entries :  2810612 : Total  Size=   22491336 bytes  File Size  =     104722 *
*Baskets :       54 : Basket Size=    1346048 bytes  Compression= 214.76     *
*............................................................................*
*Br    5 :R3BEventHeader.fTpat :                                             *
*         | UShort_t cbmout.EventHeader.R3BEventHeader.fTpat                 *
*Entries :  2810612 : Total  Size=    5625042 bytes  File Size  =      28324 *
*Baskets :       32 : Basket Size=     336896 bytes  Compression= 198.56     *
*............................................................................*
...

*Br  101 :SofToFWSingleTcalData : Int_t cbmout.SofToFW.SofToFWSingleTcalData_*
*Entries :  2810612 : Total  Size=   22639827 bytes  File Size  =    4309622 *
*Baskets :     1068 : Basket Size=      32000 bytes  Compression=   5.24     *
*............................................................................*
*Br  102 :SofToFWSingleTcalData.fUniqueID :                                  *
*         | UInt_t fUniqueID[cbmout.SofToFW.SofToFWSingleTcalData_]          *
*Entries :  2810612 : Total  Size=   12312523 bytes  File Size  =     798450 *
*Baskets :       55 : Basket Size=    1684992 bytes  Compression=  15.42     *
*............................................................................*
*Br  103 :SofToFWSingleTcalData.fBits :                                      *
*         | UInt_t fBits[cbmout.SofToFW.SofToFWSingleTcalData_]              *
*Entries :  2810612 : Total  Size=   12312287 bytes  File Size  =     798579 *
*Baskets :       55 : Basket Size=    1684992 bytes  Compression=  15.42     *
*............................................................................*
*Br  104 :SofToFWSingleTcalData.fDetector :                                  *
*         | Int_t fDetector[cbmout.SofToFW.SofToFWSingleTcalData_]           *
*Entries :  2810612 : Total  Size=   12312523 bytes  File Size  =     949779 *
*Baskets :       55 : Basket Size=    1684992 bytes  Compression=  12.96     *
*............................................................................*
*Br  105 :SofToFWSingleTcalData.fRawTofNs :                                  *
*         | Double_t fRawTofNs[cbmout.SofToFW.SofToFWSingleTcalData_]        *
*Entries :  2810612 : Total  Size=   13375377 bytes  File Size  =    2814216 *
*Baskets :       57 : Basket Size=    1767936 bytes  Compression=   4.75     *
*............................................................................*
*Br  106 :SofToFWSingleTcalData.fRawPosNs :                                  *
*         | Double_t fRawPosNs[cbmout.SofToFW.SofToFWSingleTcalData_]        *
*Entries :  2810612 : Total  Size=   13375377 bytes  File Size  =    2531125 *
*Baskets :       57 : Basket Size=    1767936 bytes  Compression=   5.28     *
*............................................................................*
*Br  107 :SofToFWSingleTcalData.fRawTimeNs :                                 *
*         | Double_t fRawTimeNs[cbmout.SofToFW.SofToFWSingleTcalData_]       *
*Entries :  2810612 : Total  Size=   13375438 bytes  File Size  =    2814518 *
*Baskets :       57 : Basket Size=    1767936 bytes  Compression=   4.75     *
*............................................................................*
....

So the TTree has (amongs others) the TBranch " SofToFWSingleTcalData" and this branch has the leaf “SofToFWSingleTcalData.fRawTimeNs”.

Thanks in advance for your help!

Tobias

[Wile_E_Coyote]

Try:

{
  TH1D *h = new TH1D("h_raw_pos", "SofToFWSingleTcalData fRawTimeNs;time;#counts", 10000, -10., 10.);
  TFile *f = TFile::Open("data_s444_main0038.root");
  TTree *t; f->GetObject("evt", t);
  gROOT->cd(); // where the "h_raw_pos" histogram resides
  t->Project("h_raw_pos", "SofToFWSingleTcalData.fRawTimeNs");
  TCanvas *c2 = new TCanvas("c2", "c2");
  h->Draw(""); // e.g. "" or "HIST"
}

[jenegger]

Hi Wile_E_Coyote,
I actually get an unfilled histogram with no entries…

Regards
Tobias

[Wile_E_Coyote]

I guess we would need your ROOT file for inspection.

You could also try:

t->Scan("SofToFWSingleTcalData.fRawTimeNs");
t->Scan("fRawTimeNs"); // SofSciTcalData.fRawTimeNs

[jenegger]

Hi Wile_E_Coyote,
here is actually a link for my ROOT file: https://www.dropbox.com/s/enhvvwcxbv4a05s/data_s444_main0038.root?dl=0

I also tried to scan both
SofToFWSingleTcalData.fRawTimeNs and fRawTimeNs but I don’t see anything strange there…

Regards
Tobias

[Wile_E_Coyote]

I improved my example source code above so that it produces a nonempty “h_raw_pos” histogram.

@pcanal However, I’m afraid that this tree is complex enough that it often requires dictionaries for classes that it uses (i.e. you will not have luck with a simple “MakeClass” generated code).

[jenegger]

Hi Wile_E_Coyote,
thanks a lot, the code snipped:

gROOT->cd();

made the change! For me is still seems some magic …

Thanks again
Tobias

[Wile_E_Coyote]

@pcanal The “evt->MakeClass();” generates some bad variables (maybe one should fix the “MakeClass” and related methods so that they always produce proper names), e.g.:

   // "space" inside
   const Int_t kMaxcbmout_MWPC0 Cal_Mwpc0CalData = 36;
   // "minus" inside
   const Int_t kMaxcbmout_TofW-Hit_TofWHitData = 1;
   // "spaces" and "dots" inside
   UInt_t          Mwpc0CalData_fUniqueID[kMaxcbmout_MWPC0 Cal_Mwpc0CalData];   //[cbmout.MWPC0 Cal.Mwpc0CalData_]
   // "minuses" and "dots" inside
   UInt_t          TofWHitData_fUniqueID[kMaxcbmout_TofW-Hit_TofWHitData];   //[cbmout.TofW-Hit.TofWHitData_]
   // "space" inside
   TBranch        *b_cbmout_MWPC0 Cal_Mwpc0CalData_;   //!
   // "minus" inside
   TBranch        *b_cbmout_TofW-Hit_TofWHitData_;   //!
   // "space"  inside
   fChain->SetBranchAddress("Mwpc0CalData", &Mwpc0CalData_, &b_cbmout_MWPC0 Cal_Mwpc0CalData_);
   // "minus" inside
   fChain->SetBranchAddress("TofWHitData", &TofWHitData_, &b_cbmout_TofW-Hit_TofWHitData_);