Counts in the number of tracks

General Chat
1

Dear All,
Trying to use this command:

[] Double_t integ = dcalphaboard ->Integral();

to find count in the number tracks from a TH2D histogram.
Then I would like to plot a TGraph using this result.

Can someone kindly assist me, please?

Thank you

2

Do you have a minimum working example (MWE)? It is difficult to understand what your issue is from your description.

3

Hey,

Thank you for your respond. Here is one of the .png file, there are many of these histograms that I would like to get Integral then plot a TGraph vs run-number.

image
image.png1252×777 13 KB

Thank you.

4

Maybe something like this:

{
  TGraph *g = new TGraph();
  g->SetTitle("number of tracks;run number;dcalphaboard integral");
  Int_t ifirst = 1; // the first run
  Int_t ilast = 79; // the last run
  for (Int_t i = ifirst; i <= ilast; i++) {
    // open the "i"-th ROOT file, retrieve the "dcalphaboard" and then ...
    Double_t integ = dcalphaboard->Integral();
    Double_t runno = i;
    g->SetPoint(g->GetN(), runno, integ); // add the "next" point to the graph
    // ... close the "i"-th ROOT file (deletes "dcalphaboard")
  }
  g->Draw("AL");
}
5

Thank to so much for your response.

I am reading in these histogram from a file of several other different histograms. Then I am trying to calculate all the normalized integrals of these histograms. Then plotting these normalized integral against run number using TGraph and save new histograms to a new file.

From the code below, I have messed up the code some where but not sure where, need some help, please.

i_ntracks = new TGraph();
i_ntracks->SetName(“i_ntracks”);
TCanvas *ac = new TCanvas(“ac”,“ac”,800,600);
while ( runflist >> rootfile )
{
run = getrun(rootfile);
Double_t n_maxbins;

t_file[n_runs] = new TFile(rootfile,“READ”);
htrig[n_runs] = (TH1*)t_file[n_runs]->Get(“htrig”)
Double_t nevents = htrig[n_runs]->GetBinContent(1);
//trying to go over all the run number
for(int inbins = 1; inbins <= n_maxbins;inbins ++)
{
for (int iarm=0; iarm<2; iarm++)
{
for (int iside=0; iside<2; iside++)
{
name = “h_dcalphaboard”; name += iarm; name += iside;
h_dcalphaboard[n_runs][iarm][iside] = (TH2*)t_file[n_runs]->Get(name);
Double_t intgel = h_dcalphaboard[n_runs][iarm][iside] ->Integral()/htrig[nruns]->GetBinContent(1);//finding the normalized number of tracks
}
h_dcalphaboard[n_runs][iarm][iside]->Fill( intgel, n_runs );//fill histogram with intgel and run number
//print intgel and Tgraph
TGraph * f = new TGraph;

TFile *savefile = new TFile(“dcalpha.root”,“RECREATE”);//save to file
}