CreateHybridLibrary_module.cc

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////////////////////////////////////////////////////////////////////////
// Chris Backhouse, UCL, Nov 2017
////////////////////////////////////////////////////////////////////////

#include "art/Framework/Core/EDAnalyzer.h"
#include "art/Framework/Core/ModuleMacros.h"
#include "larcore/Geometry/Geometry.h"
#include "larcorealg/Geometry/OpDetGeo.h"

#include <iostream>

#include "larsim/PhotonPropagation/PhotonVisibilityService.h"

#include "TF1.h"
#include "TFile.h"
#include "TGraph.h"
#include "TH1.h"
#include "TTree.h"
#include "TCanvas.h"
#include "TStyle.h"
#include "TVectorD.h"

#define PI 3.14159265

namespace fhicl { class ParameterSet; }

namespace phot
{
        class CreateHybridLibrary: public art::EDAnalyzer
        {
                public:
                        explicit CreateHybridLibrary(const fhicl::ParameterSet& p);

                        // Plugins should not be copied or assigned.
                        CreateHybridLibrary(const CreateHybridLibrary&) = delete;
                        CreateHybridLibrary(CreateHybridLibrary&&) = delete;
                        CreateHybridLibrary& operator=(const CreateHybridLibrary&) = delete;
                        CreateHybridLibrary& operator=(CreateHybridLibrary&&) = delete;

                        void analyze(const art::Event& e) override;
        };

        //--------------------------------------------------------------------
        CreateHybridLibrary::CreateHybridLibrary(const fhicl::ParameterSet& p)
                : EDAnalyzer(p)
        {

                art::ServiceHandle<geo::Geometry const> geom;

                art::ServiceHandle<phot::PhotonVisibilityService const> pvs;
                sim::PhotonVoxelDef voxdef = pvs->GetVoxelDef();

                TFile* fout_full = new TFile("full.root", "RECREATE");
                TFile* fout_fit = new TFile("fit.root", "RECREATE");

                std::cout << voxdef.GetNVoxels() << " voxels for each of " << geom->NOpDets() << " OpDets" << std::endl;
                std::cout << std::endl;

                //EP = Exception points: the parameterization is not a good description of the visibility and the value of the Photon Library is kept.
                long totExceptions = 0;
                long totPts = 0;

                for(unsigned int opdetIdx =0; opdetIdx < geom->NOpDets(); ++opdetIdx){
                  std::cout << opdetIdx << " / " << geom->NOpDets() << std::endl;

                        TDirectory* d_full = fout_full->mkdir(TString::Format("opdet_%d", opdetIdx).Data());
                        TDirectory* d_fit = fout_fit->mkdir(TString::Format("opdet_%d", opdetIdx).Data());

                        d_full->cd();
                        TTree* tr_full = new TTree("tr", "tr");
                        int vox, taken;
                        float dist, vis, psi, theta, xpos;
                        tr_full->Branch("vox", &vox);
                        tr_full->Branch("dist", &dist);
                        tr_full->Branch("vis", &vis);
                        tr_full->Branch("taken", &taken);
                        tr_full->Branch("psi", &psi); //not needed to parameterize the visibilities, useful for tests in SP
                        tr_full->Branch("theta", &theta); //not needed to parameterize the visibilities, useful for tests in SP
                        tr_full->Branch("xpos", &xpos); //not needed to parameterize the visibilities, useful for tests in SP

                        const geo::OpDetGeo& opdet = geom->OpDetGeoFromOpDet(opdetIdx);
                        auto const opdetCenter = opdet.GetCenter();
                        //std::cout << "OpDet position " << opdetIdx << ": " << opdetCenter << std::endl;

                        struct Visibility{
                          Visibility(int vx, int t, float d, float v, float p, float th, float xp) : vox(vx), taken(t), dist(d), vis(v), psi(p), theta(th), xpos(xp) {}
                                int vox;
                                int taken;
                                float dist;
                                float vis;
                                float psi;
                                float theta;
                                float xpos;
                        };
                        TCanvas *c1=new TCanvas("c1", "c1");
                        //c1->SetCanvasSize(1500, 1500);
                        c1->SetWindowSize(600, 600);
                        //c1->Divide(1,2);
                        TGraph g;
                        TGraph g2;

                        std::vector<Visibility> viss;
                        viss.reserve(voxdef.GetNVoxels());

                        for(unsigned int voxIdx = 0U; voxIdx < voxdef.GetNVoxels(); ++voxIdx){

                                const auto voxvec = voxdef.GetPhotonVoxel(voxIdx).GetCenter();
                                const double xyzvox[] = {voxvec.X(), voxvec.Y(), voxvec.Z()};
                                const double fc_y = 600; //624cm is below the center of the first voxel outside the Field Cage
                                const double fc_z = 1394;
                                const double fc_x = 350;
                                taken = 0;
                                //DP does not need variable "taken" because all voxels are inside the Field Cage for the Photon Library created in LightSim.
                                //DP taken = 1;
                                dist = opdet.DistanceToPoint(voxvec);
                                vis = pvs->GetVisibility(xyzvox, opdetIdx); // TODO use Point_t when available
                                // all voxels outside the Field Cage would be assigned these values of psi and theta
                                psi = 100;
                                theta = 200;
                                xpos = voxvec.X();

                                if((voxvec.X() - opdetCenter.X())<0){
                                  psi = atan((voxvec.Y() - opdetCenter.Y())/(-voxvec.X() +opdetCenter.X()));
                                }

                                if(voxvec.X()<fc_x && voxvec.X()>-fc_x && voxvec.Y()<fc_y && voxvec.Y()>-fc_y && voxvec.Z()> -9 && voxvec.Z()<fc_z){
                                  g.SetPoint(g.GetN(), dist, vis*dist*dist);
                                  taken = 1;
                                  psi = atan((voxvec.Y() - opdetCenter.Y())/(voxvec.X() - opdetCenter.X()))* 180.0/PI ; // psi takes values within (-PI/2, PI/2)
                                  theta = acos((voxvec.Z() - opdetCenter.Z())/dist) * 180.0/PI;  // theta takes values within (0 (beam direction, z), PI (-beam direction, -z))

                                  if((voxvec.X() - opdetCenter.X())<0){
                                  psi = atan((voxvec.Y() - opdetCenter.Y())/(-voxvec.X() +opdetCenter.X()));
                                  }

                                }
                                tr_full->Fill();
                                viss.emplace_back(voxIdx, taken, dist, vis, psi, theta, xpos);
                        } // end for voxIdx

                        d_full->cd();
                        tr_full->Write();
                        delete tr_full;

                        g.SetMarkerStyle(7);
                        c1->cd();
                        g.Draw("ap");
                        g.GetXaxis()->SetTitle("Distance (cm)");
                        g.GetYaxis()->SetTitle("Visibility #times r^{2}");
                        g.Fit("expo");
                        TF1* fit = g.GetFunction("expo");

                        d_fit->cd();
                        TVectorD fitres(2);
                        fitres[0] = fit->GetParameter(0);
                        fitres[1] = fit->GetParameter(1);
                        fitres.Write("fit");

                        gPad->SetLogy();

                        TH1F h("", "", 200, 0, 20);

                        d_fit->cd();
                        TTree* tr_fit = new TTree("tr", "tr");
                        tr_fit->Branch("vox", &vox);
                        tr_fit->Branch("dist", &dist);
                        tr_fit->Branch("vis", &vis);
                        tr_fit->Branch("taken", &taken);
                        tr_fit->Branch("psi", &psi);
                        tr_fit->Branch("theta", &theta);
                        tr_fit->Branch("xpos", &xpos);


                        for(const Visibility& v: viss){
                                // 2e-5 is the magic scaling factor to get back to integer photon
                                // counts. TODO this will differ for new libraries, should work out a
                                // way to communicate it or derive it.
                                const double obs = v.vis / 2e-5; //taken from the Photon Library
                                const double pred = fit->Eval(v.dist) / (v.dist*v.dist) / 2e-5; //calculated with parameterization

                                //DP const double obs = v.vis / 1e-7; //magic scaling factor for DP library created in LightSim
                                //Minimal amount of detected photons is 50, bc of Landau dustribution
                                //Those voxels with detected photons < 50 were set to 0
                                //DP const double pred = fit->Eval(v.dist) / (v.dist*v.dist) / 1e-7; //calculated with parametrisation
                                //std::cout << "observed = "<<obs<<" predicted (by parametrization) = "<<pred <<std::endl;


                                // Log-likelihood ratio for poisson statistics
                                double chisq = 2*(pred-obs);
                                if(obs) chisq += 2*obs*log(obs/pred);

                                vox = v.vox;
                                dist = v.dist;
                                vis = pred *2e-5;
                                psi = v.psi;
                                theta = v.theta;
                                xpos = v.xpos;
                                //DP vis = pred *1e-7;


                                if (v.taken==1){
                                  h.Fill(chisq);
                                }


                                if(chisq > 9){ //equivalent to more than 9 chisquare = 3 sigma    //maybe play around with this cutoff
                                        g2.SetPoint(g2.GetN(), v.dist, v.vis*v.dist*v.dist);
                                        vis = obs *2e-5;
                                        //DP vis = obs *1e-7;
                                        tr_fit->Fill();
                                }

                        }

                        d_fit->cd();
                        tr_fit->Write();
                        delete tr_fit;
                        g2.SetMarkerSize(1);
                        g2.SetLineWidth(3);
                        g2.SetMarkerStyle(7);
                        g2.SetMarkerColor(kRed);
                        gStyle->SetLabelSize(.04, "XY");
                        gStyle->SetTitleSize(.04,"XY");
                        c1->cd();
                        g2.Draw("p same");
                        c1->SaveAs(TString::Format("plots/Chris_vis_vs_dist_%d.png", opdetIdx).Data());


                        h.GetXaxis()->SetTitle("#chi^{2}");
                        h.GetYaxis()->SetTitle("Counts");
                        gStyle->SetLabelSize(.04, "XY");
                        gStyle->SetTitleSize(.04,"XY");
                        h.Draw("hist");
                        std::cout <<"Integral(90,-1)/Integral(all) = "<< h.Integral(90, -1) / h.Integral(0, -1) << std::endl;
                        std::cout <<"*****************************" << std::endl;
                        totExceptions += h.Integral(90, -1);
                        totPts += h.Integral(0, -1);
                        gPad->Print(TString::Format("plots/chisq_opdet_%d.eps", opdetIdx).Data());

                        delete c1;
                        } // end for opdetIdx

                        std::cout << totExceptions << " exceptions from " << totPts << " points = " << (100.*totExceptions)/totPts << "%" << std::endl;

                        delete fout_full;
                        delete fout_fit;
                        exit(0); // We're done :)
                        }

                        //--------------------------------------------------------------------
                        void CreateHybridLibrary::analyze(const art::Event&)
                        {
                        }

                        DEFINE_ART_MODULE(CreateHybridLibrary)
                } // namespace