Problem with TTree::SetBranchAddress

Erdrick · May 21, 2015, 3:35pm

I would like to use TTree::SetBranchAddress with the attached ROOT file. The attached ROOT file contains a tree with the following branches:

root [0] TFile *f1 = new TFile("trial.root","READ")
root [1] f1->ls()
TFile**         trial.root
 TFile*         trial.root
  KEY: TTree    t;1     reduced Tree
root [2] t->Print()
******************************************************************************
*Tree    :t         : reduced Tree                                           *
*Entries :     1148 : Total =          906244 bytes  File  Size =     137216 *
*        :          : Tree compression factor =   6.63                       *
******************************************************************************
*Br    0 :      energy_DSSD_low : E_DSSD_low[2][16]/I                        *
*Entries :     1148 : Total  Size=     147888 bytes  File Size  =      12840 *
*Baskets :        5 : Basket Size=      32000 bytes  Compression=  11.48     *
*............................................................................*
*Br    1 :        time_DSSD_low : t_DSSD_low[2][16]/D                        *
*Entries :     1148 : Total  Size=     295285 bytes  File Size  =      23480 *
*Baskets :       10 : Basket Size=      32000 bytes  Compression=  12.55     *
*............................................................................*
*Br    2 :multiplicity_DSSD_low : multiplicity_DSSD_low[2]/I                 *
*Entries :     1148 : Total  Size=       9813 bytes  File Size  =       1165 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=   7.96     *
*............................................................................*
*Br    3 :energy_DSSD_high : E_DSSD_high[2][16]/I                            *
*Entries :     1148 : Total  Size=     147861 bytes  File Size  =      34473 *
*Baskets :        5 : Basket Size=      32000 bytes  Compression=   4.27     *
*............................................................................*
*Br    4 :time_DSSD_high : t_DSSD_high[2][16]/D                              *
*Entries :     1148 : Total  Size=     295211 bytes  File Size  =      62520 *
*Baskets :       10 : Basket Size=      32000 bytes  Compression=   4.71     *
*............................................................................*
*Br    5 :multiplicity_DSSD_high : multiplicity_DSSD_high[2]/I               *
*Entries :     1148 : Total  Size=       9818 bytes  File Size  =       1600 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=   5.79     *
*............................................................................*

I can use TTree::SetBranchAddress for all branches except energy_DSSD_low and time_DSSD_low. For example, if I try

#include "TFile.h"
#include "TTree.h"

void showError(){

  TFile *fIn = new TFile("trial.root","READ");
  TTree *t = (TTree*) fIn->Get("t");

  int energyDSSD_low[2][16] = {{0}};
  double timeDSSD_low[2][16] = {{0.0}};
  int multiplicityDSSD_low[2] = {0};

  int energyDSSD_high[2][16] = {{0}};
  double timeDSSD_high[2][16] = {{0.0}};
  int multiplicityDSSD_high[2] = {0};
  

  int nEntries = t->GetEntries();
  for (int i=0; i<nEntries; i++){
    t->SetBranchAddress("energy_DSSD_low", &energyDSSD_low);
    t->SetBranchAddress("time_DSSD_low", &timeDSSD_low);
    t->SetBranchAddress("multiplicity_DSSD_low", &multiplicityDSSD_low);

    t->SetBranchAddress("energy_DSSD_high", &energyDSSD_high);
    t->SetBranchAddress("time_DSSD_high", &timeDSSD_high);
    t->SetBranchAddress("multiplicity_DSSD_high", &multiplicityDSSD_high);
  
  }
}

then I get

Error in <TTree::SetBranchAddress>: unknown branch -> energy_DSSD_low
Error in <TTree::SetBranchAddress>: unknown branch -> time_DSSD_low

If I try TTree::GetListOfBranches()->FindObject() for energy_DSSD_low or time_DSSD_low, null is returned. If I try TTree::GetBranchStatus() for energy_DSSD_low or time_DSSD_low, 0 is returned. Why then can I draw from these branches to make a histogram?

root [0] TFile *f1 = new TFile("trial.root")
root [1] t->GetListOfBranches()->FindObject("energy_DSSD_low")
(const class TObject*)0x0
root [2] t->GetListOfBranches()->FindObject("time_DSSD_low")
(const class TObject*)0x0
root [3] t->GetBranchStatus("energy_DSSD_low")
(const Bool_t)0
root [4] t->GetBranchStatus("time_DSSD_low")
(const Bool_t)0
root [5] t->Draw("E_DSSD_low[1][8]>>h1(30000,1,30001)","","")
Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with name c1
(Long64_t)1148

These two branches are created in the same way as all the other branches, so I do not understand why these two branches are causing trouble. If anyone has any ideas about what is happening or how to proceed from here, that would be greatly appreciated. Thanks
trial.root (139 KB)

Wile_E_Coyote · May 21, 2015, 3:44pm

You should ask the one who created this tree to use branch names without spaces inside.
A brutal fix for the existing tree could be: // ... t->SetBranchAddress(" energy_DSSD_low", &energyDSSD_low); t->SetBranchAddress(" time_DSSD_low", &timeDSSD_low); // ... Note also that you need to “t->SetBranchAddress(…)” only ONCE before you loop over tree entries.

Erdrick · May 21, 2015, 4:13pm

[quote=“Wile E. Coyote”]You should ask the one who created this tree to use branch names without spaces inside.
A brutal fix for the existing tree could be: // ... t->SetBranchAddress(" energy_DSSD_low", &energyDSSD_low); t->SetBranchAddress(" time_DSSD_low", &timeDSSD_low); // ... Note also that you need to “t->SetBranchAddress(…)” only ONCE before you loop over tree entries.[/quote]

Thank you for the reply. I will try removing the spaces in the script that creates these branches and see if that works. I do not understand your comment about “Note also that you need to “t->SetBranchAddress(…)” only ONCE before you loop over tree entries.” I think I do this. Perhaps you did not see that the first three branches end with “_low” and the last three branches end with “_high”? Thanks again.

Wile_E_Coyote · May 21, 2015, 4:45pm

[code]#include “TFile.h”
#include “TTree.h”

void showError() {
TFile *fIn = new TFile(“trial.root”,“READ”);
TTree t = (TTree) fIn->Get(“t”);

int energyDSSD_low[2][16] = {{0}};
double timeDSSD_low[2][16] = {{0.0}};
int multiplicityDSSD_low[2] = {0};

int energyDSSD_high[2][16] = {{0}};
double timeDSSD_high[2][16] = {{0.0}};
int multiplicityDSSD_high[2] = {0};

// t->SetBranchAddress(“energy_DSSD_low”, &energyDSSD_low);
t->SetBranchAddress(" energy_DSSD_low", &energyDSSD_low);
// t->SetBranchAddress(“time_DSSD_low”, &timeDSSD_low);
t->SetBranchAddress(" time_DSSD_low", &timeDSSD_low);
t->SetBranchAddress(“multiplicity_DSSD_low”, &multiplicityDSSD_low);

t->SetBranchAddress(“energy_DSSD_high”, &energyDSSD_high);
t->SetBranchAddress(“time_DSSD_high”, &timeDSSD_high);
t->SetBranchAddress(“multiplicity_DSSD_high”, &multiplicityDSSD_high);

Long64_t nEntries = t->GetEntries();
for (Long64_t i = 0; i < nEntries; i++) {
t->GetEntry(i);
// …
}

t->ResetBranchAddresses(); // detach “t” from local variables

delete fIn; // automatically deletes “t”, too
}[/code]

Erdrick · May 21, 2015, 5:09pm

[quote=“Wile E. Coyote”][code]#include “TFile.h”
#include “TTree.h”