Hi all,
I have a TH1 histogram that contains weighted events and I need the number of entries, without weight. GetEntries does not seem to work , it always gives the value one, so I thought I should use the Integral, which gives me a number. However the integral gives me the sum of weights. Is there a way to get just the number of “unweighted” events in the histogram?
Thanks!
Best regards,
Des
Suit yourself: {
// TH1::StatOverflows(kTRUE);
TH1D *h = new TH1D("h", "h", 100, -1, 1);
h->Sumw2();
for (Int_t i = 0; i < 100000; i++)
h->Fill(gRandom->Gaus(), gRandom->Rndm());
h->Draw();
std::cout << h->GetEntries() << std::endl;
std::cout << h->GetEffectiveEntries() << std::endl;
std::cout << h->Integral() << std::endl;
std::cout << h->Integral(1, h->GetNbinsX()) << std::endl;
std::cout << h->Integral(0, (h->GetNbinsX() + 1)) << std::endl;
}
Thank you Pepe Le Pew! That’s what I was looking for!