I have problem, trying to loop through a list of .root file, get histogram B, do calculation with histogram A, den put histograms A and B on same canvas, den save each individual canvas. Trouble is saving each individual histogram A and B for each file.
A sample of the code:
void contam_study()
{
char const *infile = "Bgoodndst.list";
TFile *file = TFile::Open("Atrigger_goodndst.root");
TTree *tree = (TTree*)file->Get("tree");
Int_t nevents = tree->GetEntries();
cout << "Nevents = " << nevents << endl;
Int_t s_stvar;
Float_t stvar[50];
TBranch *s_stv_branch = tree->GetBranch("s_stvar");
s_stv_branch->SetAddress(&s_stvar);
TBranch *ntv_branch = tree->GetBranch("stvar");
ntv_branch->SetAddress(&stvar);
//histogram A abd B
TH1F *hsq = new TH1F("hsq","bcq",100,0.,2500);
// hsq->SetBit(TH1::kCanRebin);
TH1F *h_sq = new TH1F("h_sq","bnsq",100,0,2500);
// get variables from fileA
for (Int_t ievt=0; ievt<n events; ievt++)
{
tree->GetEvent(ievt);
float bsum = stvar[2] + stvar[3];
hsq->Fill(bsum);
}//end of for loop
//file B files one at time, den,calculate
ifstream runlist(infile);//file stream
char filepath [900];
TFile *tfile[10000];
int nfile = 0;
if(runlist)
{
while( runlist.good() ) // continue reading file
{
runlist.getline(filepath,900);
if ( runlist.eof() ) break;
tfile[nfile] = new TFile(filepath, "read");
if ( tfile[nfile] )
{
tfile[nfile]->GetObject("h_sum",h_sq);
}
TCanvas *bb = new TCanvas("bb","A/B_sum",550,425);
TH1 *histo = hsq->Clone("histo");
histo->Divide(h_sq);
TF1 *poly0 = new TF1("poly0","pol0",1800,2000);
histo->Fit(poly0,"R");
gPad->SetLogy(1);
Double_t scale = poly0->GetParameter(0);
cout << "scale = " << scale << endl;
THStack *hs = new THStack("hs","Stacked histogram");
hs->Add(hsq);
hsq->SetLineColor(4);
hs->Add(h_sq);
h_sq->SetLineColor(2);
h_sq->Scale(scale);
hs->Draw();
tfile[nfile]->Close(); //lock di file
nfile++;//stepwise
}
}
else
{
cout << "file " << infile << " does not exist" << endl;
}
//fi save indiv plots
TFile *h = new TFile("outfile.root", "RECREATE");
h->cd();
hs->Write();//fi di individual files out.
runlist.close();//close list file.
}//end of void
to just before the creation of hsq and h_sq (TH1F *hsq = new TH1F…), and move these two
h->cd();
hs->Write();
inside the while loop over runlist, just after hs->Draw();
Since you are saving many different hs stacks, you should give them different names, e.g. something like
hs->Write(Form("hs%d",nfile));
instead of Write().
And don’t forget to close the root file at the end of your macro
Thank you so much dastudillo, for your response.
The file are been saved individually but I am seeing the two different histogram, not sure what is happening now. Here is an example:
I have another concern regarding the same macro above, I am trying to reset the THStack in the loop each time I draw before moving on to the next file.
hs->Reset();
but I got error: Can’t call THStack::Reset(), how can I reset the THStack each time?
Can you kindly make me suggestions to fix this error?
If you show the code people can give better help by seeing what exactly you are trying; as you know from my first answer, it’s not only the commands you use but where they are. Where are you trying to call GetStack? Maybe try doing it before closing tfile[nfile]?
Couet,
Thank you so much for your assistance.
Yes the macro runs however the line: hs->GetStack()->Clear(); gives error: Error: illegal pointer to class object GetStack() 0x0 70
If I comment it out no error but histograms is overlaying each other on each turn through the loop but I would like to reset the hs each time through the loop.
I don’t know how to reset the THStack on each turn, can you kindly suggest me?
Cheers
