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 19.9471 5
created -9.1 39.8942 10
created -8.5 23.9365 6
created -7.9 23.9365 6
created -7.3 35.9048 9
created -6.7 11.9683 3
created -6.1 11.9683 3
created -5.5 3.98942 1
created -4.9 27.926 7
created -4.3 15.9577 4
created -3.7 39.8942 10
created -3.1 31.9154 8
created -2.5 15.9577 4
created -1.9 11.9683 3
created -1.3 31.9154 8
created -0.7 3.98942 1
created -0.1 23.9365 6
created 0.5 39.8942 10
created 1.1 27.926 7
created 1.7 19.9471 5
created 2.3 35.9048 9
created 2.9 39.8942 10
created 3.5 3.98942 1
created 4.1 31.9154 8
created 4.7 3.98942 1
created 5.3 11.9683 3
created 5.9 19.9471 5
created 6.5 3.98942 1
created 7.1 35.9048 9
created 7.7 15.9577 4
created 8.3 35.9048 9
created 8.9 23.9365 6
created 9.5 19.9471 5
the total number of created peaks = 33 with sigma = 0.1
the total number of found peaks = 33 with sigma = 0.100002 (+-3.46611e-05)
fit chi^2 = 3.54074e-06
found -9.1 (+-0.000260936) 39.894 (+-0.1027) 10.0001 (+-0.000842808)
found -3.7 (+-0.000261026) 39.8941 (+-0.102705) 10.0002 (+-0.000842847)
found 0.5 (+-0.00026123) 39.8941 (+-0.102714) 10.0002 (+-0.000842924)
found 2.9 (+-0.000260334) 39.894 (+-0.102676) 10.0001 (+-0.000842607)
found -7.3 (+-0.000274824) 35.9046 (+-0.0974207) 9.00011 (+-0.000799482)
found 2.3 (+-0.000275784) 35.9049 (+-0.0974625) 9.00019 (+-0.000799825)
found 7.1 (+-0.000273805) 35.9044 (+-0.0973794) 9.00006 (+-0.000799143)
found 8.3 (+-0.00027505) 35.9046 (+-0.09743) 9.00013 (+-0.000799559)
found -3.1 (+-0.000292561) 31.9155 (+-0.0918908) 8.00018 (+-0.000754101)
found -1.3 (+-0.000290332) 31.915 (+-0.0918069) 8.00005 (+-0.000753412)
found 4.1 (+-0.000289607) 31.9149 (+-0.0917812) 8.00002 (+-0.000753201)
found 1.1 (+-0.000313327) 27.9262 (+-0.0859754) 7.00019 (+-0.000705557)
found -4.9 (+-0.000310854) 27.9257 (+-0.0858929) 7.00006 (+-0.000704879)
found -8.5 (+-0.000339117) 23.9369 (+-0.0796185) 6.00021 (+-0.000653389)
found 8.9 (+-0.000338702) 23.9368 (+-0.0796059) 6.00018 (+-0.000653285)
found -7.9 (+-0.000338946) 23.9369 (+-0.0796131) 6.00019 (+-0.000653344)
found -0.0999969 (+-0.000337307) 23.9367 (+-0.0795682) 6.00014 (+-0.000652976)
found -9.7 (+-0.000370941) 19.9473 (+-0.0726632) 5.00013 (+-0.00059631)
found 1.7 (+-0.000372167) 19.9476 (+-0.0726989) 5.00021 (+-0.000596603)
found 5.9 (+-0.000368122) 19.9469 (+-0.0725997) 5.00005 (+-0.000595788)
found 9.5 (+-0.000367295) 19.9473 (+-0.0725912) 5.00014 (+-0.000595719)
found -4.3 (+-0.000417264) 15.9583 (+-0.0650488) 4.00022 (+-0.000533822)
found -2.5 (+-0.000415246) 15.958 (+-0.0650072) 4.00014 (+-0.000533481)
found 7.7 (+-0.000417567) 15.9583 (+-0.0650551) 4.00023 (+-0.000533874)
found -6.7 (+-0.000481097) 11.9687 (+-0.0563236) 3.00016 (+-0.000462219)
found -6.1 (+-0.000476735) 11.9683 (+-0.0562567) 3.00005 (+-0.00046167)
found -1.9 (+-0.000481367) 11.9687 (+-0.0563271) 3.00016 (+-0.000462248)
found 5.3 (+-0.000477813) 11.9684 (+-0.0562735) 3.00008 (+-0.000461808)
found 3.5 (+-0.000851064) 3.99028 (+-0.0326195) 1.00023 (+-0.000267691)
found -0.700004 (+-0.00084756) 3.99008 (+-0.0325984) 1.00018 (+-0.000267518)
found 4.69999 (+-0.000843608) 3.98992 (+-0.0325761) 1.00014 (+-0.000267335)
found 6.50001 (+-0.000847257) 3.99007 (+-0.0325969) 1.00018 (+-0.000267506)
found -5.49999 (+-0.00084272) 3.98987 (+-0.0325707) 1.00013 (+-0.000267291)

 
#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.