Array of TH1F* problem

ROOT
1

I’m trying to merge some histograms into one (I have to fit a background distribution compounded by several channels). For each bin, I take the max value among the various histos. I’m accustomed to use STL so I would like to use vectors.

typedef vector<TH1F> HistVector_t;
typedef vector<TH1F>::const_iterator HistVectorItr;

HistVector_t bkg_vec;
bkg_vec.push_back(&h_j1);
.
.
.
bkg_vec.push_back(&h_j8);
TH1F* h_bkg = MergeHistograms(bkg_vec, hmodel, sout);

Here it is MergeHistogram:

TH1F* MergeHistograms(HistVector_t &hvec, TH1F* hmodel, ostream& sout) {

  TH1F* h_bkg = (TH1F*)hmodel->Clone("h_bkg");
  sout << endl << "Merging "<< hvec.size() << " background histograms." << endl;  

  for(Int_t binc = 1; binc <h_bkg>GetNbinsX(); binc++) {    //for each bin
  
    vector<Float_t> values;
	sout << "Bin " << binc <<endl>GetBinContent(binc);   // fill values vector
	   //sout << "value = " << vtemp << endl;
       values.push_back(vtemp);
    }
    //find max element
	sout << "Finding max el.." << endl;
    vector<Float_t>::iterator melement = max_element( values.begin(), values.end() );
    //sout << "Bin: " << binc << ", value= " << melement <<endl>SetBinContent(binc, (*melement) );
  }
  
  return h_bkg;
}

When I launch the macro, ROOT says:
*** Break *** bus error
Debugging the code, the error is here:

I’ve got another error if I remove brackets, or if I use double deference **.

Thank you in advance

2

Can you, please, attach small macro, reproducing you problem?
Telepathy does not exist, so it’s difficult to understand, what’s in your missed code and code, broken by this forum’s formatting.

3

By the way, to find max/min bin content, you do not need to copy bin content
from hist into vector, and lookup in this vector with std::max/min element - at least it looks strange. Use hist specific:
TH1F::GetMaximum if you want max value or TH1F::GetMaximumBin if you want index.

4

I am very sorry for this ugly misformatting. In attachment you can find a macro with the same problem.
BTW, I’m using ROOT v5.04/00 20 September 2005 on a Mac Mini PPC.
testmacro.C (1.76 KB)

5

Forum’s formatting is not you fault :slight_smile:)

  1. You take an adress of h2 and h3 - thats wrong, they are pointers already, you should push them directly.
  2. include algorithm heade to use max_element, and use qualification
    std::max_element
  3. My previous letter about GetMaximum can be ignored :slight_smile: (that’s becuase of formatting :slight_smile:) )
  4. Must be (*it)->GetBinContent(…), not (*it).GetBinContent().
    expression *it has type TH1F *.
  5. (advice) Do not create vector inside a loop, create it outside and call
    values.clear() before you start filling it in the inner loop
vector<Float_t> values;
for(....) {    //for each bin
      values.clear();
     for(...) {
///////
       values.push_back(vtemp);
    }
  }
6

Ok, thank you very much. Now it’s working properly. All the mess started with this wrong push_back. :blush:

Cheers