FitAwmi.C File Reference

Detailed Description

This macro fits the source spectrum using the AWMI algorithm from the "TSpectrumFit" class ("TSpectrum" class is used to find peaks).

To try this macro, in a ROOT (5 or 6) prompt, do:

root > .x FitAwmi.C

or:

root > .x FitAwmi.C++
root > FitAwmi(); // re-run with another random set of peaks

 
created -9.7 31.9154 8
created -9.1 31.9154 8
created -8.5 7.97885 2
created -7.9 3.98942 1
created -7.3 23.9365 6
created -6.7 11.9683 3
created -6.1 11.9683 3
created -5.5 15.9577 4
created -4.9 11.9683 3
created -4.3 19.9471 5
created -3.7 27.926 7
created -3.1 3.98942 1
created -2.5 3.98942 1
created -1.9 3.98942 1
created -1.3 11.9683 3
created -0.7 23.9365 6
created -0.1 31.9154 8
created 0.5 27.926 7
created 1.1 31.9154 8
created 1.7 7.97885 2
created 2.3 39.8942 10
created 2.9 7.97885 2
created 3.5 39.8942 10
created 4.1 7.97885 2
created 4.7 27.926 7
created 5.3 3.98942 1
created 5.9 3.98942 1
created 6.5 27.926 7
created 7.1 35.9048 9
created 7.7 35.9048 9
created 8.3 39.8942 10
created 8.9 7.97885 2
created 9.5 3.98942 1
the total number of created peaks = 33 with sigma = 0.1
the total number of found peaks = 33 with sigma = 0.100002 (+-1.79137e-05)
fit chi^2 = 7.98115e-07
found 2.3 (+-0.000123213) 39.8937 (+-0.0487284) 10.0001 (+-0.000399889)
found 3.5 (+-0.000123213) 39.8937 (+-0.0487284) 10 (+-0.000399889)
found 8.3 (+-0.000123765) 39.894 (+-0.0487545) 10.0001 (+-0.000400103)
found 7.1 (+-0.000131032) 35.9049 (+-0.0462766) 9.00021 (+-0.000379768)
found 7.7 (+-0.000131217) 35.9051 (+-0.0462849) 9.00024 (+-0.000379837)
found -9.7 (+-0.000138788) 31.9152 (+-0.043619) 8.0001 (+-0.000357959)
found -9.1 (+-0.000138503) 31.9153 (+-0.0436122) 8.00013 (+-0.000357903)
found -0.0999997 (+-0.000138888) 31.9154 (+-0.0436263) 8.00017 (+-0.000358019)
found 1.1 (+-0.00013843) 31.9152 (+-0.0436092) 8.00012 (+-0.000357879)
found -3.7 (+-0.000147697) 27.9257 (+-0.0407834) 7.00008 (+-0.000334689)
found 0.5 (+-0.000148887) 27.9262 (+-0.040823) 7.00021 (+-0.000335014)
found 4.7 (+-0.000147289) 27.9256 (+-0.0407699) 7.00004 (+-0.000334578)
found 6.5 (+-0.000148042) 27.9259 (+-0.0407957) 7.00013 (+-0.00033479)
found -7.3 (+-0.00015939) 23.9363 (+-0.0377538) 6.00005 (+-0.000309827)
found -0.699998 (+-0.000160434) 23.9366 (+-0.0377837) 6.00014 (+-0.000310072)
found -4.3 (+-0.00017589) 19.9472 (+-0.0344952) 5.00013 (+-0.000283084)
found -5.5 (+-0.000196304) 15.9577 (+-0.0308462) 4.00008 (+-0.000253139)
found -6.7 (+-0.000227901) 11.9685 (+-0.0267324) 3.00012 (+-0.00021938)
found -6.1 (+-0.000227456) 11.9684 (+-0.0267254) 3.00009 (+-0.000219322)
found -4.9 (+-0.000227975) 11.9685 (+-0.0267334) 3.00012 (+-0.000219387)
found -1.3 (+-0.000227058) 11.9684 (+-0.0267204) 3.00009 (+-0.000219281)
found 1.7 (+-0.000282724) 7.97963 (+-0.0218663) 2.00023 (+-0.000179445)
found 2.9 (+-0.000283154) 7.97973 (+-0.0218712) 2.00026 (+-0.000179486)
found -8.50001 (+-0.000279535) 7.97916 (+-0.0218327) 2.00012 (+-0.00017917)
found 4.1 (+-0.000282482) 7.97957 (+-0.0218635) 2.00022 (+-0.000179423)
found 8.89999 (+-0.00027995) 7.97927 (+-0.0218376) 2.00014 (+-0.00017921)
found -3.10001 (+-0.000397888) 3.98976 (+-0.0154522) 1.0001 (+-0.000126808)
found 5.29999 (+-0.000397888) 3.98977 (+-0.0154522) 1.00011 (+-0.000126808)
found -7.89999 (+-0.000398723) 3.98976 (+-0.015456) 1.0001 (+-0.000126839)
found 5.90001 (+-0.000397888) 3.98977 (+-0.0154522) 1.00011 (+-0.000126808)
found 9.5 (+-0.000390856) 3.9895 (+-0.0154179) 1.00004 (+-0.000126527)
found -2.5 (+-0.00039348) 3.98945 (+-0.0154274) 1.00003 (+-0.000126605)
found -1.9 (+-0.00039562) 3.98955 (+-0.0154389) 1.00005 (+-0.000126699)

 
#include "TROOT.h"
#include "TMath.h"
#include "TRandom.h"
#include "TH1.h"
#include "TF1.h"
#include "TCanvas.h"
#include "TSpectrum.h"
#include "TSpectrumFit.h"
#include "TPolyMarker.h"
#include "TList.h"
 
#include <iostream>
 
TH1F *FitAwmi_Create_Spectrum(void) {
   Int_t nbins = 1000;
   Double_t xmin = -10., xmax = 10.;
   delete gROOT->FindObject("h"); // prevent "memory leak"
   TH1F *h = new TH1F("h", "simulated spectrum", nbins, xmin, xmax);
   h->SetStats(kFALSE);
   TF1 f("f", "TMath::Gaus(x, [0], [1], 1)", xmin, xmax);
   // f.SetParNames("mean", "sigma");
   gRandom->SetSeed(0); // make it really random
   // create well separated peaks with exactly known means and areas
   // note: TSpectrumFit assumes that all peaks have the same sigma
   Double_t sigma = (xmax - xmin) / Double_t(nbins) * Int_t(gRandom->Uniform(2., 6.));
   Int_t npeaks = 0;
   while (xmax > (xmin + 6. * sigma)) {
      npeaks++;
      xmin += 3. * sigma; // "mean"
      f.SetParameters(xmin, sigma);
      Double_t area = 1. * Int_t(gRandom->Uniform(1., 11.));
      h->Add(&f, area, ""); // "" ... or ... "I"
      std::cout << "created "
                << xmin << " "
                << (area / sigma / TMath::Sqrt(TMath::TwoPi())) << " "
                << area << std::endl;
      xmin += 3. * sigma;
   }
   std::cout << "the total number of created peaks = " << npeaks
             << " with sigma = " << sigma << std::endl;
   return h;
}
 
void FitAwmi(void) {
 
   TH1F *h = FitAwmi_Create_Spectrum();
 
   TCanvas *cFit = ((TCanvas *)(gROOT->GetListOfCanvases()->FindObject("cFit")));
   if (!cFit) cFit = new TCanvas("cFit", "cFit", 10, 10, 1000, 700);
   else cFit->Clear();
   h->Draw("L");
   Int_t i, nfound, bin;
   Int_t nbins = h->GetNbinsX();
 
   Double_t *source = new Double_t[nbins];
   Double_t *dest = new Double_t[nbins];
 
   for (i = 0; i < nbins; i++) source[i] = h->GetBinContent(i + 1);
   TSpectrum *s = new TSpectrum(); // note: default maxpositions = 100
   // searching for candidate peaks positions
   nfound = s->SearchHighRes(source, dest, nbins, 2., 2., kFALSE, 10000, kFALSE, 0);
   // filling in the initial estimates of the input parameters
   Bool_t *FixPos = new Bool_t[nfound];
   Bool_t *FixAmp = new Bool_t[nfound];
   for(i = 0; i < nfound; i++) FixAmp[i] = FixPos[i] = kFALSE;
 
   Double_t *Pos, *Amp = new Double_t[nfound]; // ROOT 6
 
   Pos = s->GetPositionX(); // 0 ... (nbins - 1)
   for (i = 0; i < nfound; i++) {
      bin = 1 + Int_t(Pos[i] + 0.5); // the "nearest" bin
      Amp[i] = h->GetBinContent(bin);
   }
   TSpectrumFit *pfit = new TSpectrumFit(nfound);
   pfit->SetFitParameters(0, (nbins - 1), 1000, 0.1, pfit->kFitOptimChiCounts,
                          pfit->kFitAlphaHalving, pfit->kFitPower2,
                          pfit->kFitTaylorOrderFirst);
   pfit->SetPeakParameters(2., kFALSE, Pos, FixPos, Amp, FixAmp);
   // pfit->SetBackgroundParameters(source[0], kFALSE, 0., kFALSE, 0., kFALSE);
   pfit->FitAwmi(source);
   Double_t *Positions = pfit->GetPositions();
   Double_t *PositionsErrors = pfit->GetPositionsErrors();
   Double_t *Amplitudes = pfit->GetAmplitudes();
   Double_t *AmplitudesErrors = pfit->GetAmplitudesErrors();
   Double_t *Areas = pfit->GetAreas();
   Double_t *AreasErrors = pfit->GetAreasErrors();
   delete gROOT->FindObject("d"); // prevent "memory leak"
   TH1F *d = new TH1F(*h); d->SetNameTitle("d", ""); d->Reset("M");
   for (i = 0; i < nbins; i++) d->SetBinContent(i + 1, source[i]);
   Double_t x1 = d->GetBinCenter(1), dx = d->GetBinWidth(1);
   Double_t sigma, sigmaErr;
   pfit->GetSigma(sigma, sigmaErr);
 
   // current TSpectrumFit needs a sqrt(2) correction factor for sigma
   sigma /= TMath::Sqrt2(); sigmaErr /= TMath::Sqrt2();
   // convert "bin numbers" into "x-axis values"
   sigma *= dx; sigmaErr *= dx;
 
   std::cout << "the total number of found peaks = " << nfound
             << " with sigma = " << sigma << " (+-" << sigmaErr << ")"
             << std::endl;
   std::cout << "fit chi^2 = " << pfit->GetChi() << std::endl;
   for (i = 0; i < nfound; i++) {
      bin = 1 + Int_t(Positions[i] + 0.5); // the "nearest" bin
      Pos[i] = d->GetBinCenter(bin);
      Amp[i] = d->GetBinContent(bin);
 
      // convert "bin numbers" into "x-axis values"
      Positions[i] = x1 + Positions[i] * dx;
      PositionsErrors[i] *= dx;
      Areas[i] *= dx;
      AreasErrors[i] *= dx;
 
      std::cout << "found "
                << Positions[i] << " (+-" << PositionsErrors[i] << ") "
                << Amplitudes[i] << " (+-" << AmplitudesErrors[i] << ") "
                << Areas[i] << " (+-" << AreasErrors[i] << ")"
                << std::endl;
   }
   d->SetLineColor(kRed); d->SetLineWidth(1);
   d->Draw("SAME L");
   TPolyMarker *pm = ((TPolyMarker*)(h->GetListOfFunctions()->FindObject("TPolyMarker")));
   if (pm) {
      h->GetListOfFunctions()->Remove(pm);
      delete pm;
   }
   pm = new TPolyMarker(nfound, Pos, Amp);
   h->GetListOfFunctions()->Add(pm);
   pm->SetMarkerStyle(23);
   pm->SetMarkerColor(kRed);
   pm->SetMarkerSize(1);
   // cleanup
   delete pfit;
   delete [] Amp;
   delete [] FixAmp;
   delete [] FixPos;
   delete s;
   delete [] dest;
   delete [] source;
   return;
}

Author

Definition in file FitAwmi.C.