FFTJetPileupProcessor.cc

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// -*- C++ -*-
//
// Package:    RecoJets/FFTJetProducers
// Class:      FFTJetPileupProcessor
// 
//
// Original Author:  Igor Volobouev
//         Created:  Wed Apr 20 13:52:23 CDT 2011
//
//

#include <cmath>
#include <fstream>

// FFTJet headers
#include "fftjet/FrequencyKernelConvolver.hh"
#include "fftjet/DiscreteGauss2d.hh"
#include "fftjet/EquidistantSequence.hh"
#include "fftjet/interpolate.hh"

// framework include files
#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/MakerMacros.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "DataFormats/Common/interface/View.h"
#include "DataFormats/JetReco/interface/DiscretizedEnergyFlow.h"

#include "RecoJets/FFTJetAlgorithms/interface/gridConverters.h"

// parameter parser header
#include "RecoJets/FFTJetProducers/interface/FFTJetParameterParser.h"

// useful utilities collected in the second base
#include "RecoJets/FFTJetProducers/interface/FFTJetInterface.h"

// Loader for the lookup tables
#include "JetMETCorrections/FFTJetObjects/interface/FFTJetLookupTableSequenceLoader.h"


using namespace fftjetcms;

//
// class declaration
//
class FFTJetPileupProcessor : public FFTJetInterface
{
public:
    explicit FFTJetPileupProcessor(const edm::ParameterSet&);
    ~FFTJetPileupProcessor() override;

protected:
    // methods
    void beginJob() override ;
    void produce(edm::Event&, const edm::EventSetup&) override;
    void endJob() override ;

private:
    FFTJetPileupProcessor() = delete;
    FFTJetPileupProcessor(const FFTJetPileupProcessor&) = delete;
    FFTJetPileupProcessor& operator=(const FFTJetPileupProcessor&) = delete;

    void buildKernelConvolver(const edm::ParameterSet&);
    void mixExtraGrid();
    void loadFlatteningFactors(const edm::EventSetup& iSetup);

    // The FFT engine
    std::unique_ptr<MyFFTEngine> engine;

    // The pattern recognition kernel(s)
    std::unique_ptr<fftjet::AbsFrequencyKernel> kernel2d;

    // The kernel convolver
    std::unique_ptr<fftjet::AbsConvolverBase<Real> > convolver;

    // Storage for convolved energy flow
    std::unique_ptr<fftjet::Grid2d<fftjetcms::Real> > convolvedFlow;

    // Filtering scales
    std::unique_ptr<fftjet::EquidistantInLogSpace> filterScales;

    // Eta-dependent factors to use for flattening the distribution
    // _after_ the filtering
    std::vector<double> etaFlatteningFactors;

    // Number of percentile points to use
    unsigned nPercentiles;

    // Bin range. Both values of 0 means use the whole range.
    unsigned convolverMinBin;
    unsigned convolverMaxBin;

    // Density conversion factor
    double pileupEtaPhiArea;

    // Variable related to mixing additional grids
    std::vector<std::string> externalGridFiles;
    std::ifstream gridStream;
    double externalGridMaxEnergy;
    unsigned currentFileNum;

    // Some memory to hold the percentiles found
    std::vector<double> percentileData;

    // Variables to load the flattening factors from
    // the calibration database (this has to be done
    // in sync with configuring the appropriate event
    // setup source)
    std::string flatteningTableRecord;
    std::string flatteningTableName;
    std::string flatteningTableCategory;
    bool loadFlatteningFactorsFromDB;
};

//
// constructors and destructor
//
FFTJetPileupProcessor::FFTJetPileupProcessor(const edm::ParameterSet& ps)
    : FFTJetInterface(ps),
      etaFlatteningFactors(
          ps.getParameter<std::vector<double> >("etaFlatteningFactors")),
      nPercentiles(ps.getParameter<unsigned>("nPercentiles")),
      convolverMinBin(ps.getParameter<unsigned>("convolverMinBin")),
      convolverMaxBin(ps.getParameter<unsigned>("convolverMaxBin")),
      pileupEtaPhiArea(ps.getParameter<double>("pileupEtaPhiArea")),
      externalGridFiles(ps.getParameter<std::vector<std::string> >("externalGridFiles")),
      externalGridMaxEnergy(ps.getParameter<double>("externalGridMaxEnergy")),
      currentFileNum(externalGridFiles.size() + 1U),
      flatteningTableRecord(ps.getParameter<std::string>("flatteningTableRecord")),
      flatteningTableName(ps.getParameter<std::string>("flatteningTableName")),
      flatteningTableCategory(ps.getParameter<std::string>("flatteningTableCategory")),
      loadFlatteningFactorsFromDB(ps.getParameter<bool>("loadFlatteningFactorsFromDB"))
{
    // Build the discretization grid
    energyFlow = fftjet_Grid2d_parser(
        ps.getParameter<edm::ParameterSet>("GridConfiguration"));
    checkConfig(energyFlow, "invalid discretization grid");

    // Copy of the grid which will be used for convolutions
    convolvedFlow = std::unique_ptr<fftjet::Grid2d<fftjetcms::Real> >(
        new fftjet::Grid2d<fftjetcms::Real>(*energyFlow));

    // Make sure the size of flattening factors is appropriate
    if (!etaFlatteningFactors.empty())
    {
        if (etaFlatteningFactors.size() != convolvedFlow->nEta())
            throw cms::Exception("FFTJetBadConfig")
                << "ERROR in FFTJetPileupProcessor constructor:"
                " number of elements in the \"etaFlatteningFactors\""
                " vector is inconsistent with the discretization grid binning"
                << std::endl;
    }

    // Build the FFT engine(s), pattern recognition kernel(s),
    // and the kernel convolver
    buildKernelConvolver(ps);

    // Build the set of pattern recognition scales
    const unsigned nScales = ps.getParameter<unsigned>("nScales");
    const double minScale = ps.getParameter<double>("minScale");
    const double maxScale = ps.getParameter<double>("maxScale");
    if (minScale <= 0.0 || maxScale < minScale || nScales == 0U)
        throw cms::Exception("FFTJetBadConfig")
            << "invalid filter scales" << std::endl;

    filterScales = std::unique_ptr<fftjet::EquidistantInLogSpace>(
        new fftjet::EquidistantInLogSpace(minScale, maxScale, nScales));

    percentileData.resize(nScales*nPercentiles);

    produces<reco::DiscretizedEnergyFlow>(outputLabel);
    produces<std::pair<double,double> >(outputLabel);
}


void FFTJetPileupProcessor::buildKernelConvolver(const edm::ParameterSet& ps)
{
    // Get the eta and phi scales for the kernel(s)
    double kernelEtaScale = ps.getParameter<double>("kernelEtaScale");
    const double kernelPhiScale = ps.getParameter<double>("kernelPhiScale");
    if (kernelEtaScale <= 0.0 || kernelPhiScale <= 0.0)
        throw cms::Exception("FFTJetBadConfig")
            << "invalid kernel scales" << std::endl;

    if (convolverMinBin || convolverMaxBin)
        if (convolverMinBin >= convolverMaxBin || 
            convolverMaxBin > energyFlow->nEta())
            throw cms::Exception("FFTJetBadConfig")
                << "invalid convolver bin range" << std::endl;

    // FFT assumes that the grid extent in eta is 2*Pi. Adjust the
    // kernel scale in eta to compensate.
    kernelEtaScale *= (2.0*M_PI/(energyFlow->etaMax() - energyFlow->etaMin()));

    // Build the FFT engine
    engine = std::unique_ptr<MyFFTEngine>(
        new MyFFTEngine(energyFlow->nEta(), energyFlow->nPhi()));

    // 2d kernel
    kernel2d = std::unique_ptr<fftjet::AbsFrequencyKernel>(
        new fftjet::DiscreteGauss2d(
            kernelEtaScale, kernelPhiScale,
            energyFlow->nEta(), energyFlow->nPhi()));

    // 2d convolver
    convolver = std::unique_ptr<fftjet::AbsConvolverBase<Real> >(
        new fftjet::FrequencyKernelConvolver<Real,Complex>(
            engine.get(), kernel2d.get(),
            convolverMinBin, convolverMaxBin));
}


FFTJetPileupProcessor::~FFTJetPileupProcessor()
{
}


// ------------ method called to produce the data  ------------
void FFTJetPileupProcessor::produce(
    edm::Event& iEvent, const edm::EventSetup& iSetup)
{
    loadInputCollection(iEvent);
    discretizeEnergyFlow();

    // Determine the average Et density for this event.
    // Needs to be done here, before mixing in another grid.
    const fftjet::Grid2d<Real>& g(*energyFlow);
    const double densityBeforeMixing = g.sum()/pileupEtaPhiArea;

    // Mix an extra grid (if requested)
    double densityAfterMixing = -1.0;
    if (!externalGridFiles.empty())
    {
        mixExtraGrid();
        densityAfterMixing = g.sum()/pileupEtaPhiArea;
    }

    // Various useful variables
    const unsigned nScales = filterScales->size();
    const double* scales = &(*filterScales)[0];
    Real* convData = const_cast<Real*>(convolvedFlow->data());
    Real* sortData = convData + convolverMinBin*convolvedFlow->nPhi();
    const unsigned dataLen = convolverMaxBin ? 
        (convolverMaxBin - convolverMinBin)*convolvedFlow->nPhi() :
        convolvedFlow->nEta()*convolvedFlow->nPhi();

    // Load flattenning factors from DB (if requested)
    if (loadFlatteningFactorsFromDB)
        loadFlatteningFactors(iSetup);

    // Go over all scales and perform the convolutions
    convolver->setEventData(g.data(), g.nEta(), g.nPhi());
    for (unsigned iscale=0; iscale<nScales; ++iscale)
    {
        // Perform the convolution
        convolver->convolveWithKernel(
            scales[iscale], convData,
            convolvedFlow->nEta(), convolvedFlow->nPhi());

        // Apply the flattening factors
        if (!etaFlatteningFactors.empty())
            convolvedFlow->scaleData(&etaFlatteningFactors[0],
                                     etaFlatteningFactors.size());

        // Sort the convolved data
        std::sort(sortData, sortData+dataLen);

        // Determine the percentile points
        for (unsigned iper=0; iper<nPercentiles; ++iper)
        {
            // Map percentile 0 into point number 0, 
            // 1 into point number dataLen-1
            const double q = (iper + 0.5)/nPercentiles;
            const double dindex = q*(dataLen-1U);
            const unsigned ilow = static_cast<unsigned>(std::floor(dindex));
            const double percentile = fftjet::lin_interpolate_1d(
                ilow, ilow+1U, sortData[ilow], sortData[ilow+1U], dindex);

            // Store the calculated percentile
            percentileData[iscale*nPercentiles + iper] = percentile;
        }
    }

    // Convert percentile data into a more convenient storable object
    // and put it into the event record
    iEvent.put(std::make_unique<reco::DiscretizedEnergyFlow>(
            &percentileData[0], "FFTJetPileupProcessor",
            -0.5, nScales-0.5, 0.0, nScales, nPercentiles), outputLabel);

    iEvent.put(std::make_unique<std::pair<double,double>>(densityBeforeMixing, densityAfterMixing), outputLabel);
}


void FFTJetPileupProcessor::mixExtraGrid()
{
    const unsigned nFiles = externalGridFiles.size();
    if (currentFileNum > nFiles)
    {
        // This is the first time this function is called
        currentFileNum = 0;
        gridStream.open(externalGridFiles[currentFileNum].c_str(),
                        std::ios_base::in | std::ios_base::binary);
        if (!gridStream.is_open())
            throw cms::Exception("FFTJetBadConfig")
                << "ERROR in FFTJetPileupProcessor::mixExtraGrid():"
                " failed to open external grid file "
                << externalGridFiles[currentFileNum] << std::endl;
    }

    const fftjet::Grid2d<float>* g = nullptr;
    const unsigned maxFail = 100U;
    unsigned nEnergyRejected = 0;

    while(!g)
    {
        g = fftjet::Grid2d<float>::read(gridStream);

        // If we can't read the grid, we need to switch to another file
        for (unsigned ntries=0; ntries<nFiles && g == nullptr; ++ntries)
        {
            gridStream.close();
            currentFileNum = (currentFileNum + 1U) % nFiles;
            gridStream.open(externalGridFiles[currentFileNum].c_str(),
                            std::ios_base::in | std::ios_base::binary);
            if (!gridStream.is_open())
                throw cms::Exception("FFTJetBadConfig")
                    << "ERROR in FFTJetPileupProcessor::mixExtraGrid():"
                    " failed to open external grid file "
                    << externalGridFiles[currentFileNum] << std::endl;
            g = fftjet::Grid2d<float>::read(gridStream);
        }

        if (g)
            if (g->sum() > externalGridMaxEnergy)
            {
                delete g;
                g = nullptr;
                if (++nEnergyRejected >= maxFail)
                    throw cms::Exception("FFTJetBadConfig")
                        << "ERROR in FFTJetPileupProcessor::mixExtraGrid():"
                        " too many grids in a row (" << nEnergyRejected
                        << ") failed the maximum energy cut" << std::endl;
            }
    }

    if (g)
    {
        add_Grid2d_data(energyFlow.get(), *g);
        delete g;
    }
    else
    {
        // Too bad, no useful file found
        throw cms::Exception("FFTJetBadConfig")
            << "ERROR in FFTJetPileupProcessor::mixExtraGrid():"
            " no valid grid records found" << std::endl;
    }
}


// ------------ method called once each job just before starting event loop
void FFTJetPileupProcessor::beginJob()
{
}


// ------------ method called once each job just after ending the event loop
void FFTJetPileupProcessor::endJob()
{
}


void FFTJetPileupProcessor::loadFlatteningFactors(const edm::EventSetup& iSetup)
{
    edm::ESHandle<FFTJetLookupTableSequence> h;
    StaticFFTJetLookupTableSequenceLoader::instance().load(
        iSetup, flatteningTableRecord, h);
    boost::shared_ptr<npstat::StorableMultivariateFunctor> f =
        (*h)[flatteningTableCategory][flatteningTableName];

    // Fill out the table of flattening factors as a function of eta
    const unsigned nEta = energyFlow->nEta();
    etaFlatteningFactors.clear();
    etaFlatteningFactors.reserve(nEta);
    for (unsigned ieta=0; ieta<nEta; ++ieta)
    {
        const double eta = energyFlow->etaBinCenter(ieta);
        etaFlatteningFactors.push_back((*f)(&eta, 1U));
    }
}


//define this as a plug-in
DEFINE_FWK_MODULE(FFTJetPileupProcessor);