histogram display in peak search

From: Kazuyoshi Furutaka <furutaka.kazuyoshi_at_jaea.go.jp>
Date: Thu, 14 Dec 2006 14:27:50 +0900 (JST)

Dear rooters,

Could someone teach me

  1. why the attached script (named 'peakSearchTest.C'), which try to find candidate of peaks from TH1F "hpx" in "hsimple.root" using TSpectrum::Search(), DISPLAYS the histogram when run as an unnamed script (.x peakSearchTest.C), whereas it does not when run as a named one (by invoking peakSearchTest() after loading the script (or `.x peakSearchTest.C`), of course after uncommenting the function name in the script and commenting out the first curly brace.)?

   In the latter, only an empty canvas is displayed...    (though a candidate is successfully found)

2. whether it is possible to seach peaks using TSpectrum::Search()

   without displaying any canvas/histogram (or control    its display) in interactive root sessions (i.e. w/o    -b option) or not?

   Even though the histogram is not explicitly drawn,    the attached script (when run as unnamed one) displays    it.

Thanks in advance.


Kazuyoshi Furutaka
furutaka _dot_ kazuyoshi _at_ jaea _dot_ go _dot_ jp

#if !defined(__CINT__)
# include "TCanvas.h"
# include "TH1.h"
# include "TFile.h"
# include "TSpectrum.h"
{ //void peakSearchTest() { // create a canvas TCanvas *c1 = new TCanvas("c1","c1",10,10,800,500); // read and draw a histogram from a file TFile f("hsimple.root"); TH1F *h = (TH1F*)f.Get("hpx"); //h->Draw(); // search a peak, maxpositions=1, resolution=1(default) TSpectrum *s = new TSpectrum(2); // in histogram 'h', sigma=2, options="", thresh.=0.10 Int_t npfound = s->Search(h,2,"",0.10); if ( npfound > 0 ) { Float_t *xpeaks = s->GetPositionX(); for ( Int_t np=0 ; np < npfound ; np++ ) { Float_t xp = *(xpeaks+np); Int_t bin = h->GetXaxis()->FindBin(xp); printf("Found a candidate of peak at %d channel.\n", bin); } } }

Received on Thu Dec 14 2006 - 06:28:24 MET

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