ShowerPCAEigenvalueLength_tool.cc

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//############################################################################
//### Name:        ShowerPCAEigenvalueLength                               ###
//### Author:      Ed Tyley                                                ###
//### Date:        07.01.20                                                ###
//### Description: Simple code to calculate the lenght from the PCA        ###
//###              eigenvalues                                             ###
//############################################################################

//Framework Includes
#include "art/Utilities/ToolMacros.h"

//LArSoft Includes
#include "lardataobj/RecoBase/PCAxis.h"
#include "larpandora/LArPandoraEventBuilding/LArPandoraShower/Tools/IShowerTool.h"

namespace ShowerRecoTools {

  class ShowerPCAEigenvalueLength : public IShowerTool {

  public:
    ShowerPCAEigenvalueLength(const fhicl::ParameterSet& pset);

    //Generic Direction Finder
    int CalculateElement(const art::Ptr<recob::PFParticle>& pfparticle,
                         art::Event& Event,
                         reco::shower::ShowerElementHolder& ShowerEleHolder) override;

  private:
    art::InputTag fPFParticleLabel;
    int fVerbose;
    std::string fShowerPCAInputLabel;
    std::string fShowerLengthOutputLabel;
    std::string fShowerOpeningAngleOutputLabel;
    float fNSigma;
  };

  ShowerPCAEigenvalueLength::ShowerPCAEigenvalueLength(const fhicl::ParameterSet& pset)
    : IShowerTool(pset.get<fhicl::ParameterSet>("BaseTools"))
    , fPFParticleLabel(pset.get<art::InputTag>("PFParticleLabel"))
    , fVerbose(pset.get<int>("Verbose"))
    , fShowerPCAInputLabel(pset.get<std::string>("ShowerPCAInputLabel"))
    , fShowerLengthOutputLabel(pset.get<std::string>("ShowerLengthOutputLabel"))
    , fShowerOpeningAngleOutputLabel(pset.get<std::string>("ShowerOpeningAngleOutputLabel"))
    , fNSigma(pset.get<float>("NSigma"))
  {}

  int ShowerPCAEigenvalueLength::CalculateElement(
    const art::Ptr<recob::PFParticle>& pfparticle,
    art::Event& Event,
    reco::shower::ShowerElementHolder& ShowerEleHolder)
  {

    if (!ShowerEleHolder.CheckElement(fShowerPCAInputLabel)) {
      if (fVerbose)
        mf::LogError("ShowerPCAEigenvalueLength") << "PCA not set, returning " << std::endl;
      return 1;
    }

    recob::PCAxis PCA = recob::PCAxis();
    ShowerEleHolder.GetElement(fShowerPCAInputLabel, PCA);

    const double* eigenValues = PCA.getEigenValues();

    // The PCA eigenvalues give the deviance of space points around the center
    // Take the sqrt to get std. dev and take fNSigma in each direction:
    // Call the length fNSigma x 2 x std. dev. along primary eigenvalues
    // Call the width fNSigma x 2 x std. dev. along secondary eigenvalues

    //TODO: Actually calculate the erros (Maybe fNSigma+-1Sigma?)

    //Find the length
    double primaryEigenValue = (eigenValues)[0];
    double ShowerLength = std::sqrt(primaryEigenValue) * 2 * fNSigma;
    double ShowerLengthError = -999;

    //Find the width of the shower
    double secondaryEigenValue = (eigenValues)[1];
    double ShowerWidth = std::sqrt(secondaryEigenValue) * 2 * fNSigma;

    double ShowerAngle = std::atan(ShowerWidth / ShowerLength);
    double ShowerAngleError = -999;

    // Fill the shower element holder
    ShowerEleHolder.SetElement(ShowerLength, ShowerLengthError, fShowerLengthOutputLabel);
    ShowerEleHolder.SetElement(ShowerAngle, ShowerAngleError, fShowerOpeningAngleOutputLabel);

    return 0;
  }
}

DEFINE_ART_CLASS_TOOL(ShowerRecoTools::ShowerPCAEigenvalueLength)