Re: histogram display in peak search

Hi,

Kazuyoshi Furutaka wrote:
> 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)
>

Replace
  TFile f("hsimple.root");
by
  TFile *f = new TFile("hsimple.root");
For more details read chapter about Object Ownership in Users Guide
> 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.
>
>

Use option "goff", ie
  Int_t npfound = s->Search(h,2,"goff",0.10); see doc at http://root.cern.ch/root/htmldoc/TSpectrum.html#TSpectrum:Search

Rene Brun
>
> Thanks in advance.
>
> Yours,
> Kazuyoshi
> --
> 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"
> #endif
>
> {
> //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 - 09:40:27 MET