// root.cern.ch/root/htmldoc/guides/spectrum/Spectrum.html#dimensional-spectra
// root.cern.ch/doc/master/Background__order_8C.html

// Example to illustrate the influence of the clipping filter difference order
// on the estimated background.
//
// Authors Miroslav Morhac, Olivier Couet


void Background_order ()
{
  Int_t i;
  Int_t nbins = 4096;
  Double_t xmin     = 0;
  Double_t xmax     = 4096;
  Double_t* source  = new Double_t [nbins];
  gROOT->ForceStyle ();

  TFile* f    = new TFile ("TSpectrum.root");
  TH1F* hdata = (TH1F*) f->Get("back2");
  hdata->SetTitle ("Influence of clipping filter difference order on the estimated background");
  hdata->SetAxisRange (1220, 1460);
  hdata->SetMaximum (3400);
  hdata->Draw ("L");

  TSpectrum* Analyser1dim = new TSpectrum ();

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);


  /*** Testing for filter order = 2 ***/

  Analyser1dim->Background (
            source, nbins, 40, TSpectrum::kBackDecreasingWindow,
            TSpectrum::kBackOrder2, kFALSE,
            TSpectrum::kBackSmoothing3, kFALSE );

/*
    const char* TSpectrum::Background (
     Double_t* spectrum,      pointer to the array of source spectrum
     Int_t ssize,             length of the spectrum vector
     Int_t numberIterations,  maximal width of clipping window,
     Int_t direction,         direction of change of clipping window.
                              Possible values: kBackIncreasingWindow, kBackDecreasingWindow
     Int_t filterOrder,       order of clipping filter. Possible values:
                              kBackOrder2, kBackOrder4, kBackOrder6, kBackOrder8
     bool  smoothing,         logical variable whether the smoothing operation in the
                              estimation of background will be included. (0/1)
     Int_t smoothWindow,      width of smoothing window. Possible values:
                              kBackSmoothing3, kBackSmoothing5, ..., kBackSmoothing15
     bool  compton            whether the estimation of Compton edge will be included. (0/1)
   )

   See: root.cern.ch/doc/v608/classTSpectrum.html#a7830480612d1ee301964e6c79319f444
*/

  TH1F* horder2 = new TH1F ("horder2", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) horder2->SetBinContent (i+1, source[i]);
  horder2->SetLineColor(kRed);
  horder2->Draw("SAME L");


  /*** Testing for filter order = 4 ***/

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);

  Analyser1dim->Background (
                source, nbins, 40, TSpectrum::kBackDecreasingWindow,
                TSpectrum::kBackOrder4, kFALSE,
                TSpectrum::kBackSmoothing3, kFALSE );

  TH1F* horder4 = new TH1F ("horder4", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) horder4->SetBinContent (i+1, source[i]);
  horder4->SetLineColor (kBlue);
  horder4->Draw ("SAME L");


  /*** Testing for filter order = 6 ***/

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);

  Analyser1dim->Background (
                source, nbins, 40, TSpectrum::kBackDecreasingWindow,
                TSpectrum::kBackOrder6, kFALSE,
                TSpectrum::kBackSmoothing3, kFALSE );

  TH1F* horder6 = new TH1F ("horder6", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) horder6->SetBinContent (i+1, source[i]);
  horder6->SetLineColor (kGreen);
  horder6->Draw ("SAME L");


  /*** Testing for filter order = 8 ***/

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);

  Analyser1dim->Background (
                source, nbins, 40, TSpectrum::kBackDecreasingWindow,
                TSpectrum::kBackOrder8, kFALSE,
                TSpectrum::kBackSmoothing3, kFALSE );

  TH1F* horder8 = new TH1F ("horder8", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) horder8->SetBinContent (i+1, source[i]);
  horder8->SetLineColor (kMagenta);
  horder8->Draw ("SAME L");


  gStyle->SetOptStat (0);
  
  TLegend* legend = new TLegend (0.1, 0.7, 0.48, 0.9);
  legend->AddEntry (hdata  , "Data"     , "l");
  legend->AddEntry (horder2, "Order = 2", "l");
  legend->AddEntry (horder4, "Order = 4", "l");
  legend->AddEntry (horder6, "Order = 6", "l");
  legend->AddEntry (horder8, "Order = 8", "l");
  legend->Draw();
}