Hi Bob,
You are reading two branches only of your Tree. Probably, you have
more branches. Do you have objects in those branches?
Anyhow, I suggest the following simplification and changes in
your script.
- use a local TH1F. It will be automatically deleted when leaving
the function
- read only the two branches. Will be faster
- Use the TH1::Integral instead of your loop. Your loop did not start
at bin 1.
void weighthist(TTree *t, TString name, int nbins, double xmin, double xmax)
{
double val, weight;
double binwidth = (xmax-xmin)/nbins;
int nentries = (int)t->GetEntries();
int i;
TH1F hist ("hist-" + name, name + " distribution", nbins, xmin, xmax);
TBranch *bval = t->GetBranch(name);
TBranch *bw = t->GetBranch("weight");
bval->SetAddress(&val);
bw->SetAddress(&weight);
for(i=0;i<nentries;i++) {
bval->GetEntry(i);
bw->GetEntry(i);
hist->Fill(val,weight);
}
cout << "Integral is: " << hist.Integral("width") << endl;
}
About your second question. To execute a CINT command in a macro,
use gROOT->ProcessLine. Example
gROOT->ProcessLine(".L ~/.root/weighthist.C");
Rene Brun
Bob McElrath wrote:
>
> I'm having trouble running a couple of simple scripts to make hisograms
> from TTree data:
>
> // Draws a weighted histogram. The tree you pass must have a branch named "weight"
> // that will be applied.
> void weighthist(TTree *t, TString name, int nbins, double xmin, double xmax)
> {
> TH1F *hist;
> double val, weight;
> double binwidth = (xmax-xmin)/nbins;
> int nentries = (int)t->GetEntries();
> int i;
> double integral=0.0;
>
> if(hist = (TH1F*)gROOT->FindObject("hist-" + name)) delete hist;
> hist = new TH1F("hist-" + name, name + " distribution", nbins, xmin, xmax);
> if(!hist) {
> cout << "new failed for TH1F!" << endl;
> return;
> }
> t->SetBranchAddress(name, &val);
> t->SetBranchAddress("weight", &weight);
> for(i=0;i<nentries;i++) {
> t->GetEntry(i);
> hist->Fill(val,weight);
> }
> for(i=0;i<nbins;i++) {
> integral += binwidth*hist->GetBinContent(i);
> }
> cout << "Integral is: " << integral << endl;
> }
>
> I then run this script a couple of times:
> root [1] .L ~/.root/weighthist.C
> root [2] TFile f("ppmumu.root", "UPDATE");
> root [3] TTree *t = (TTree*)f.Get("ppgammazmumu");
> root [4] TTree *st = (TTree*)f.Get("pphmumu");
> root [5] weighthist(t, "q", 50, 50, 200);
> Integral is: 3.20927e+12
> root [6] weighthist(t, "ptl", 50, 0, 200);
> Integral is: 4.28335e+12
> root [7] weighthist(t, "costheta", 50, -1, 1);
>
> *** Break *** segmentation violation
> Root > Function weighthist() busy flag cleared
>
> What does that mean?!? And how do I fix it? Note that the function ran
> successfully *twice* before bombing. Turning on debug (gDebug=1) does
> not provide any more information than the above. (about the segfault,
> anyway)
>
> Lastly, where can I put commands like .L ~/.root/weighthist.C so I can
> load a set of often-used scripts at startup? Scripts don't seem to like
> dot commands (.L) or I'd put it in login.C or something.
>
> Thanks,
> -- Bob
>
> Bob McElrath (rsmcelrath@students.wisc.edu)
> Univ. of Wisconsin at Madison, Department of Physics
>
> --------------------------------------------------------------------------------
>
> Part 1.2 Type: application/pgp-signature
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