SideBandSubtraction.cc

Go to the documentation of this file.

// Author: David Bjergaard
//
// Library for Generic Sideband Subtraction Methods.
//
// This library is designed to be a tool which serves two purposes.
// Its primary purpose is to provide a generic framework for doing
// sideband subtraction.  It will also plug into current tag and probe
// modules to prevent code duplication and redundancy.
//

#include "PhysicsTools/Utilities/interface/SideBandSubtraction.h"
// System includes
#include <iostream>
#include <ios>
#include <fstream>
#include <cstdlib>
#include <sstream>

// ROOT includes
#include <TCanvas.h>
#include <TFile.h>
#include <TF1.h>
#include <TH1F.h>
#include <TString.h>
#include <TKey.h>
#include <TClass.h>

// RooFit includes
#include <RooFitResult.h>
#include <RooRealVar.h>
#include <RooAbsPdf.h>
#include <RooDataSet.h>
#include <RooPlot.h>

using namespace RooFit;
using std::cerr;
using std::cout;
using std::endl;
using std::string;
using std::vector;

template <class T>
inline std::string stringify(const T& t) {
  std::ostringstream o;
  if (!(o << t))
    return "err";
  return o.str();
}
Double_t SideBandSubtract::getYield(const std::vector<SbsRegion>& Regions, RooAbsPdf* PDF) {
  if (PDF == nullptr || SeparationVariable == nullptr)
    return 0.0;

  Double_t yield = 0;
  RooAbsReal* intPDF;
  for (unsigned int i = 0; i < Regions.size(); i++) {
    if (verbose)
      cout << "Integrating over Range: " << Regions[i].RegionName << " from " << Regions[i].min << " to "
           << Regions[i].max << endl;
    intPDF = PDF->createIntegral(*SeparationVariable, Range(Regions[i].RegionName.c_str()));
    yield += intPDF->getVal();
    if (verbose)
      cout << "Current yield: " << yield << endl;
  }
  return yield;
}
static void setHistOptions(TH1F* histo, string name, string title, string axis_label) {
  histo->SetName(name.c_str());
  histo->SetTitle(title.c_str());
  if (axis_label == "GeV/c^2")
    axis_label = "Mass (" + axis_label + ")";
  if (axis_label == "GeV/c")
    axis_label = "Momentum (" + axis_label + ")";
  histo->GetXaxis()->SetTitle(axis_label.c_str());
}
int SideBandSubtract::doSubtraction(RooRealVar* variable,
                                    Double_t stsratio,
                                    Int_t index)  //stsratio -> signal to sideband ratio
{
  if (Data == nullptr || SeparationVariable == nullptr) {
    cerr << "ERROR: Data or SeparationVariable is NULL returning now!\n";
    return -1;
  }
  TH1F* SideBandHist = (TH1F*)BaseHistos[index]->Clone();
  setHistOptions(SideBandHist,
                 (string)variable->GetName() + "Sideband",
                 (string)SideBandHist->GetTitle() + " Sideband",
                 (string)variable->getUnit());

  TH1F* SignalHist = (TH1F*)BaseHistos[index]->Clone();
  setHistOptions(SignalHist,
                 (string)variable->GetName() + "SignalHist",
                 (string)SignalHist->GetTitle() + " Raw Signal",
                 (string)variable->getUnit());

  //Begin a loop over the data to fill our histograms. I should figure
  //out how to do this in one shot to avoid a loop
  //O(N_vars*N_events)...

  TIterator* iter = (TIterator*)Data->get()->createIterator();
  RooAbsArg* var = nullptr;
  RooRealVar* sep_var = nullptr;
  while ((var = (RooAbsArg*)iter->Next())) {
    if ((string)var->GetName() == (string)SeparationVariable->GetName()) {
      sep_var = (RooRealVar*)var;
      break;
    }
  }
  for (int i = 0; i < Data->numEntries(); i++) {
    Data->get(i);
    Double_t value = variable->getVal();
    Double_t cutval = sep_var->getVal();

    for (unsigned int j = 0; j < SideBandRegions.size(); j++)  //UGLY!  Find better solution!
    {
      if (cutval > SideBandRegions[j].min && cutval < SideBandRegions[j].max)
        SideBandHist->Fill(value);
    }
    for (unsigned int j = 0; j < SignalRegions.size(); j++) {
      if (cutval > SignalRegions[j].min && cutval < SignalRegions[j].max)
        SignalHist->Fill(value);
    }
  }
  //Save pre-subtracted histo
  SignalHist->Sumw2();
  SideBandHist->Sumw2();
  //SignalHist->SetDirectory(0); SideBandHist->SetDirectory(0);
  RawHistos.push_back(*SignalHist);

  SignalHist->Add(SideBandHist, -stsratio);

  SignalHist->SetTitle(((string)BaseHistos[index]->GetTitle() + " SBS Signal").c_str());
  //Save subtracted histo
  SBSHistos.push_back(*SignalHist);
  //Save Sideband histo
  SideBandHistos.push_back(*SideBandHist);

  if (SideBandHist)
    delete SideBandHist;
  return 0;
}
static void print_histo(TH1F* plot, string outname) {
  TCanvas genericCanvas;
  plot->Draw("E1P0");
  outname = outname + ".eps";
  genericCanvas.SaveAs(outname.c_str());
  outname.replace(outname.size() - 3, 3, "gif");
  genericCanvas.SaveAs(outname.c_str());
}
void SideBandSubtract::printResults(string prefix) {  //handles *all* printing
  //spool over vectors of histograms and print them, then print
  //separation variable plots and the results text file.
  if (SeparationVariable == nullptr) {
    cerr << "ERROR: printResults, SeparationVariable is NULL!\n";
    return;
  }
  string filename;  //output file name
  for (unsigned int i = 0; i < RawHistos.size(); ++i) {
    filename = prefix + "Raw_" + (string)RawHistos[i].GetName();
    print_histo(&RawHistos[i], filename);
  }
  for (unsigned int i = 0; i < SBSHistos.size(); ++i) {
    filename = prefix + "SBS_" + (string)RawHistos[i].GetName();
    print_histo(&SBSHistos[i], filename);
  }
  if (verbose) {
    for (unsigned int i = 0; i < SideBandHistos.size(); ++i) {
      filename = prefix + "SideBand_" + (string)RawHistos[i].GetName();
      print_histo(&SideBandHistos[i], filename);
    }
  }

  string outname = prefix + (string)SeparationVariable->GetName() + "_fitted.eps";
  if (Data != nullptr && ModelPDF != nullptr) {
    RooPlot* SepVarFrame = SeparationVariable->frame();
    Data->plotOn(SepVarFrame);
    ModelPDF->plotOn(SepVarFrame);
    TCanvas Canvas;
    SepVarFrame->Draw();
    Canvas.SaveAs(outname.c_str());
    outname.replace(outname.size() - 3, 3, "gif");
    Canvas.SaveAs(outname.c_str());
  } else
    cerr << "ERROR: printResults, Data or ModelPDF is NULL!\n";

  string result_outname = prefix + "_fit_results.txt";
  std::ofstream output(result_outname.c_str(), std::ios::out);
  if (!output) {
    cout << "ERROR: Could not open file for writing!\n";
    return;
  }

  if (fit_result != nullptr) {
#if ROOT_VERSION_CODE <= ROOT_VERSION(5, 19, 0)
    fit_result->printToStream(output, Verbose);
#else
    fit_result->printMultiline(output, kTRUE);
#endif
  }
}

void SideBandSubtract::saveResults(string outname) {
  //saves the ephemeral stuff to a root file for future
  //use/modification (ie everything printed by printResults())

  TFile output(outname.c_str(), "UPDATE");  //open the output file,
                                            //create it if it doesn't
                                            //exist
  //Since keys are only available from files on disk, we need to write
  //out a new file.  If the file already existed, then we opened to
  //update, and are writing nothing new.
  output.Write();
  TString dirname;
  TIter nextkey(output.GetListOfKeys());
  TKey* key;
  TDirectory* curDir = nullptr;
  while ((key = (TKey*)nextkey.Next())) {
    if (key == nullptr)
      break;
    TObject* obj = key->ReadObj();
    if (obj->IsA()->InheritsFrom("TDirectory"))
      dirname = obj->GetName();
  }

  if (dirname == "") {
    //we didn't find any directories so, we'll make a new one
    curDir = output.mkdir("run0", "Run 0");
    output.cd("run0");
  } else {
    //manipulate last dir string, make a new one, and get ready to fill
    dirname.Remove(0, 3);
    Int_t run_num = dirname.Atoi();
    run_num++;
    dirname = "run" + stringify(run_num);
    curDir = output.mkdir(dirname.Data(), ("Run " + stringify(run_num)).c_str());
    output.cd(dirname.Data());
  }
  if (curDir == nullptr)
    curDir = output.GetDirectory("", kTRUE, "");

  //these should all be the same size, but to be pedantic we'll loop
  //over each one individually, also, we need to associate them with
  //the directory because by default they "float" in memory to avoid
  //conflicts with other root files the user has open. If they want to
  //write to those files, they need to close their file, pass the name
  //here, and then let us work.
  for (unsigned int i = 0; i < SideBandHistos.size(); ++i) {
    SideBandHistos[i].SetDirectory(curDir);
    SideBandHistos[i].Write();
  }
  for (unsigned int i = 0; i < RawHistos.size(); ++i) {
    RawHistos[i].SetDirectory(curDir);
    RawHistos[i].Write();
  }
  for (unsigned int i = 0; i < SBSHistos.size(); ++i) {
    SBSHistos[i].SetDirectory(curDir);
    SBSHistos[i].Write();
  }
  if (Data != nullptr && ModelPDF != nullptr && BackgroundPDF != nullptr && SeparationVariable != nullptr) {
    RooPlot* sep_varFrame = SeparationVariable->frame();
    Data->plotOn(sep_varFrame);
    ModelPDF->plotOn(sep_varFrame);
    BackgroundPDF->plotOn(sep_varFrame);
    sep_varFrame->Write();
  } else
    cerr << "ERROR: saveResults, did not save RooPlot of data and fit\n";
  output.Write();
}
void SideBandSubtract::setDataSet(RooDataSet* newData) {
  if (newData != nullptr)
    Data = newData;
}
void SideBandSubtract::print_plot(RooRealVar* printVar, string outname) {
  if (Data == nullptr || ModelPDF == nullptr) {
    cerr << "ERROR: print_plot, Data or ModelPDF are NULL\n";
    return;
  }

  RooPlot* genericFrame = printVar->frame();
  Data->plotOn(genericFrame);
  ModelPDF->plotOn(genericFrame);
  TCanvas genericCanvas;
  genericFrame->Draw();
  outname = outname + ".eps";
  genericCanvas.SaveAs(outname.c_str());
  outname.replace(outname.size() - 3, 3, "gif");
  genericCanvas.SaveAs(outname.c_str());
}
SideBandSubtract::SideBandSubtract()
    : BackgroundPDF(nullptr),
      ModelPDF(nullptr),
      Data(nullptr),
      SeparationVariable(nullptr),
      verbose(false),
      SignalRegions(),
      SideBandRegions(),
      SideBandHistos(0),
      RawHistos(0),
      SBSHistos(0),
      BaseHistos(0),
      fit_result(nullptr),
      SignalSidebandRatio(0) {
  // Default constructor so we can do fast subtraction
}
SideBandSubtract::SideBandSubtract(RooAbsPdf* model_shape,
                                   RooAbsPdf* bkg_shape,
                                   RooDataSet* data,
                                   RooRealVar* sep_var,
                                   const vector<TH1F*>& base,
                                   bool verb)
    : BackgroundPDF(bkg_shape),
      ModelPDF(model_shape),
      Data(data),
      SeparationVariable(sep_var),
      verbose(verb),
      SignalRegions(),
      SideBandRegions(),
      SideBandHistos(),
      RawHistos(),
      SBSHistos(),
      BaseHistos(base),
      base_histo(nullptr),
      fit_result(nullptr),
      SignalSidebandRatio(0) {}
/*
SideBandSubtract::SideBandSubtract(RooAbsPdf *model_shape, 
                   RooAbsPdf *bkg_shape, 
                   RooDataSet* data,
                   RooRealVar* sep_var,
                   bool verb
                   )
  : BackgroundPDF(bkg_shape), 
    ModelPDF(model_shape), 
    Data(data),
    SeparationVariable(sep_var),
    verbose(verb),
    SignalRegions(),
    SideBandRegions(),
    SideBandHistos(),
    RawHistos(),
    SBSHistos(),
    BaseHistos(),
    base_histo(0),
    fit_result(0),
    SignalSidebandRatio(0)
{
  // Build BaseHistos from dataset
  TIterator* iter = (TIterator*) Data->get()->createIterator();
  RooAbsArg *var=NULL;
  RooRealVar *variable=NULL;
  cout <<"Starting while loop\n";
  while((var = (RooAbsArg*)iter->Next()))
    {
      if((string)var->ClassName() != "RooRealVar")
    continue;
      variable = (RooRealVar*)var;
      //we own the data this points to so we need to delete it at the end...
      assert(variable!=NULL);
      string title = "base_"+(string)variable->GetName();
      base_histo = (TH1F*)Data->createHistogram(title.c_str(), *variable, Binning(variable->getBinning("default",verb,kTRUE)) );
      //cout <<"Made histo with name: "<<base_histo->GetName()<<endl;
      //base_histo->SetDirectory(0);
      BaseHistos.push_back(*base_histo);
      cout <<"Added histo to BaseHistos!\n Deleting local copy...";
      if(base_histo) delete base_histo;
      cout <<"Done!\n";
    }

}
*/
SideBandSubtract::~SideBandSubtract() {
  //**WARNING**

  // We don't delete objects that we don't own (duh) so, all of our
  // pointers just hang out and get handled by other people :)

  // We DO own the BaseHistos IFF the user didn't provide us with
  // them and we constructed them from the dataset... in this case
  // base_histo will be non-null and we want to delete the vector
  // of histograms...
  resetSBSProducts();
  /*
  if(base_histo!=NULL)
    {
      BaseHistos.clear();
    }
  */
}
void SideBandSubtract::addSignalRegion(Double_t min, Double_t max) {
  SbsRegion signal;
  signal.min = min;
  signal.max = max;
  signal.RegionName = "Signal" + stringify(SignalRegions.size());
  if (SeparationVariable != nullptr)
    SeparationVariable->setRange(signal.RegionName.c_str(), signal.min, signal.max);
  SignalRegions.push_back(signal);
  return;
}
void SideBandSubtract::addSideBandRegion(Double_t min, Double_t max) {
  SbsRegion sideband;
  sideband.min = min;
  sideband.max = max;
  sideband.RegionName = "SideBand" + stringify(SideBandRegions.size());
  if (SeparationVariable != nullptr)
    SeparationVariable->setRange(sideband.RegionName.c_str(), sideband.min, sideband.max);
  SideBandRegions.push_back(sideband);
  return;
}
int SideBandSubtract::doGlobalFit() {
  if (verbose)
    cout << "Beginning SideBand Subtraction\n";

  if (ModelPDF != nullptr && Data != nullptr && SeparationVariable != nullptr) {
    fit_result = ModelPDF->fitTo(*Data, "r");
  } else {
    cerr << "ERROR: doGobalFit, no ModelPDF, SeparationVariable or Data specified\n";
    return -1;
  }

  Double_t SideBandYield = getYield(SideBandRegions, BackgroundPDF);
  Double_t BackgroundInSignal = getYield(SignalRegions, BackgroundPDF);

  SignalSidebandRatio = BackgroundInSignal / SideBandYield;
  if (verbose) {
    cout << "Finished fitting background!\n";
    cout << "Attained a Signal to Sideband ratio of: " << SignalSidebandRatio << endl;
  }
  //I can't see a way around a double loop for each variable.  Maybe I
  //can get a C++/RooFit guru to save me the trouble here?

  //need to grab sbs objects after each global fit, because they get reset
  resetSBSProducts();
  TIterator* iter = (TIterator*)Data->get()->createIterator();
  RooAbsArg* variable;
  while ((variable = (RooAbsArg*)iter->Next())) {
    for (unsigned int i = 0; i < BaseHistos.size(); i++) {
      if ((string)variable->GetName() != (string)SeparationVariable->GetName() &&
          (string)variable->GetName() == (string)BaseHistos[i]->GetName())
        doSubtraction((RooRealVar*)variable, SignalSidebandRatio, i);
    }
  }

  //  clean up our memory...
  if (variable)
    delete variable;
  if (iter)
    delete iter;
  return 0;
}
void SideBandSubtract::doFastSubtraction(TH1F& Total, TH1F& Result, SbsRegion& leftRegion, SbsRegion& rightRegion) {
  Int_t binMin = Total.FindBin(leftRegion.max, 0.0, 0.0);
  Int_t binMax = Total.FindBin(leftRegion.min, 0.0, 0.0);
  double numLeft = Total.Integral(binMin, binMax);

  binMin = Total.FindBin(rightRegion.max, 0.0, 0.0);
  binMax = Total.FindBin(rightRegion.min, 0.0, 0.0);
  double numRight = Total.Integral(binMin, binMax);

  const unsigned int nbinsx = Total.GetNbinsX();
  const double x1 = (leftRegion.max + leftRegion.min) / 2.0;
  const double x2 = (rightRegion.max + rightRegion.min) / 2.0;

  const double y1 = numLeft / (leftRegion.max - leftRegion.min);
  const double y2 = numRight / (rightRegion.max - rightRegion.min);

  const double Slope = (y2 - y1) / (x2 - x1);
  const double Intercept = y1 - Slope * x1;
  // Evantually we want to handle more complicated functions, but for
  // now... just use a linear one
  TF1 function("sbs_function_line", "[0]*x + [1]", Total.GetMinimum(), Total.GetMaximum());
  for (unsigned int binx = 1; binx <= nbinsx; ++binx) {
    double binWidth = Total.GetBinWidth(binx);
    function.SetParameter(0, Slope * binWidth);
    function.SetParameter(1, Intercept * binWidth);

    double xx = Total.GetBinCenter(binx);
    double cu = Total.GetBinContent(binx) - function.Eval(xx);
    // TODO: Propogate the  error on the parameters in function.
    double error1 = Total.GetBinError(binx);

    Result.SetBinContent(binx, cu);
    Result.SetBinError(binx, error1);
  }
  Result.SetEntries(Result.Integral());
}
RooFitResult* SideBandSubtract::getFitResult() { return fit_result; }
vector<TH1F*> SideBandSubtract::getBaseHistos() { return BaseHistos; }
vector<TH1F> SideBandSubtract::getRawHistos() { return RawHistos; }
vector<TH1F> SideBandSubtract::getSBSHistos() { return SBSHistos; }
Double_t SideBandSubtract::getSTSRatio() { return SignalSidebandRatio; }
void SideBandSubtract::resetSBSProducts() {
  //cout <<"Starting to reset products \n";

  if (!SideBandHistos.empty())
    SideBandHistos.clear();

  if (!RawHistos.empty())
    RawHistos.clear();
  if (!SBSHistos.empty())
    SBSHistos.clear();
}