我在填充这个向量对时做错了什么？

Question

If I do:

vector<string> vec_jets;

double values[] = {
    transEnergy(map_jets, "jet1"),
    transEnergy(map_jets, "jet2"),
    transEnergy(map_jets, "jet3"),
    transEnergy(map_jets, "jet4"),
    transEnergy(map_jets, "jet5"),
    transEnergy(map_jets, "jet6"),
    transEnergy(map_jets, "jet7") };

for( int j = 1; j <= Njets; j++){
  oss << "jet" << j;
  vec_jets.push_back( oss.str() );
  oss.str("");
}

vector<pair<string,double> > jets_pt( vec_jets.size() );

// for( int k = 0; k < Njets; k++ ){ 
  // if( jet_preselection(map_jets,map_leps,vec_jets[k],jets_emfr[k]) )

        transform(
            vec_jets.begin(),
            vec_jets.end(), 
            values,
            jets_pt.begin(),
            make_pair<string,double>
        );

//    }  

I have the output I want, which is, for example

jet1 32.4717

But, if I uncomment the for loop and the if condition, it seems that the vector is not filled anymore, if I ask to cout it, I get only 0 always.

The function in the if statement is just a bool

bool jet_preselection(
    map<string, TLorentzVector> map_jets,
    map<string, TLorentzVector> map_leps,
    string vec_jets,
    double jet_emfr )
{

        return ( map_jets[vec_jets].E()*sin(map_jets[vec_jets].Theta()) > 15 
            && jet_emfr < 0.9
            && fabs(map_jets[vec_jets].PseudoRapidity()) > 2.5
            && ( map_jets[vec_jets].DeltaR(map_leps["lep1"]) > 0.4
                && map_jets[vec_jets].DeltaR(map_leps["lep2"]) > 0.4
                && map_jets[vec_jets].DeltaR(map_leps["lep3"]) > 0.4 );
}

Answer 1

There are a lot of complex interdependancies in your code that make it difficult to diagnose the problem. But I can tell you that in:

bool jet_preselection(map<string, TLorentzVector> map_jets, map<string, TLorentzVector> map_leps, string vec_jets, double jet_emfr)

...you are passing map_jets and map_leps by value rahter than by-reference (preferred) or by-pointer, so that when you call this function a complete copy of those map s is constructed.

You may consider changing how you pass these parameters. Perhaps passing copies of these maps would change the states of them in such a way so that jet_preselection would fail.