DisambigAlg.cxx

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//
// DisambigAlg.cxx
//
// tylerdalion@gmail.com
//
// description
//
//
// Since we are letting the module make the final column of hits, a disambiguated
// hit in this algorithm is a pair< art::Ptr<recob::Hit>, geo::WireID >
//
//

//Framework includes:
#include "art/Framework/Principal/Handle.h"
#include "fhiclcpp/ParameterSet.h"
#include "messagefacility/MessageLogger/MessageLogger.h"

#include "larcorealg/Geometry/CryostatGeo.h"
#include "larcorealg/Geometry/TPCGeo.h"
#include "lardata/ArtDataHelper/ToElement.h"
#include "lardataalg/DetectorInfo/DetectorPropertiesData.h"
#include "lardataobj/RecoBase/Hit.h"
#include "larreco/RecoAlg/DisambigAlg.h"

#include <cmath>
#include <cstdlib>
#include <map>

#include "range/v3/view.hpp"

using lar::to_element;
using ranges::views::filter;
using ranges::views::transform;

namespace apa {

  DisambigAlg::DisambigAlg(fhicl::ParameterSet const& p)
    : fAPAGeo(p.get<fhicl::ParameterSet>("APAGeometryAlg"))
  {
    fCrawl = p.get<bool>("Crawl");
    fUseEndP = p.get<bool>("UseEndP");
    fCompareViews = p.get<bool>("CompareViews");
    fCloseHitsRadius = p.get<double>("CloseHitsRadius");
    fMaxEndPDegRange = p.get<double>("MaxEndPDegRange");
    fNChanJumps = p.get<unsigned int>("NChanJumps");
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  void DisambigAlg::RunDisambig(detinfo::DetectorClocksData const& clockData,
                                detinfo::DetectorPropertiesData const& detProp,
                                art::Handle<std::vector<recob::Hit>> ChannelHits)
  {
    fUeffSoFar.clear();
    fVeffSoFar.clear();
    fnUSoFar.clear();
    fnVSoFar.clear();
    fnDUSoFar.clear();
    fnDVSoFar.clear();
    fChannelToHits.clear();
    fAPAToUVHits.clear();
    fAPAToZHits.clear();
    fAPAToHits.clear();
    fAPAToEndPHits.clear();
    fAPAToDHits.clear();
    fDisambigHits.clear();
    fChanTimeToWid.clear();
    fHasBeenDisambiged.clear();

    std::vector<art::Ptr<recob::Hit>> ChHits;
    art::fill_ptr_vector(ChHits, ChannelHits);

    fHasBeenDisambiged.clear();
    unsigned int skipNoise(0);
    // Map hits by channel/APA, initialize the disambiguation status map
    for (size_t h = 0; h < ChHits.size(); h++) {
      art::Ptr<recob::Hit> const& hit = ChHits[h];

      // **temporary** option to skip noise hits
      try {
        bt_serv->HitToXYZ(clockData, hit);
      }
      catch (...) {
        skipNoise++;
        continue;
      }

      geo::View_t view = hit->View();
      unsigned int apa(0), cryo(0);
      fAPAGeo.ChannelToAPA(hit->Channel(), apa, cryo);
      fAPAToHits[apa].push_back(hit);
      if (view == geo::kZ) {
        fAPAToZHits[apa].push_back(hit);
        continue;
      }
      else if (view == geo::kU || view == geo::kV) {
        std::pair<double, double> ChanTime(hit->Channel() * 1., hit->PeakTime() * 1.);
        this->fHasBeenDisambiged[apa][ChanTime] = false;
        fChannelToHits[hit->Channel()].push_back(hit);
        fAPAToUVHits[apa].push_back(hit);
      }
    }

    if (skipNoise > 0)
      mf::LogWarning("DisambigAlg")
        << "\nSkipped " << skipNoise << " induction noise hits using the BackTrackerService.\n"
        << "This is only to temporarily deal with the excessive amount of noise due to the bad "
           "deconvolution.\n";

    mf::LogVerbatim("RunDisambig") << "\n~~~~~~~~~~~ Running Disambiguation ~~~~~~~~~~~\n";

    std::map<unsigned int, std::vector<art::Ptr<recob::Hit>>>::iterator APA_it;
    for (APA_it = fAPAToUVHits.begin(); APA_it != fAPAToUVHits.end(); APA_it++) {
      unsigned int apa = APA_it->first;

      mf::LogVerbatim("RunDisambig") << "APA " << apa << ":";

      fUeffSoFar[apa] = 0.;
      fVeffSoFar[apa] = 0.;
      fnUSoFar[apa] = 0;
      fnVSoFar[apa] = 0;
      fnDUSoFar[apa] = 0;
      fnDVSoFar[apa] = 0;

      // Always run this...
      this->TrivialDisambig(clockData, detProp, apa);
      this->AssessDisambigSoFar(apa);
      mf::LogVerbatim("RunDisambig")
        << "  Trivial Disambig -->  " << fnDUSoFar[apa] << " / " << fnUSoFar[apa] << " U,  "
        << fnDVSoFar[apa] << " / " << fnVSoFar[apa] << " V";

      // ... and pick the rest with the configurations.
      if (fCrawl) {
        this->Crawl(apa);
        this->AssessDisambigSoFar(apa);
        mf::LogVerbatim("RunDisambig")
          << "  Crawl            -->  " << fnDUSoFar[apa] << " / " << fnUSoFar[apa] << " U,  "
          << fnDVSoFar[apa] << " / " << fnVSoFar[apa] << " V";
      }

      if (fUseEndP) {
        this->FindChanTimeEndPts(detProp, apa);
        this->UseEndPts(detProp, apa); // does the crawl from inside
        this->AssessDisambigSoFar(apa);
        mf::LogVerbatim("RunDisambig")
          << "  Endpoint Crawl   -->  " << fnDUSoFar[apa] << " / " << fnUSoFar[apa] << " U,  "
          << fnDVSoFar[apa] << " / " << fnVSoFar[apa] << " V";
      }

      if (fCompareViews) {
        unsigned int nDisambig(1);
        while (nDisambig > 0) {
          nDisambig = this->CompareViews(detProp, apa);
          this->Crawl(apa);
        }
        this->AssessDisambigSoFar(apa);
        mf::LogVerbatim("RunDisambig")
          << "  Compare Views    -->  " << fnDUSoFar[apa] << " / " << fnUSoFar[apa] << " U,  "
          << fnDVSoFar[apa] << " / " << fnVSoFar[apa] << " V";
      }

      // For now just buld a simple list to get from the module
      for (size_t i = 0; i < fAPAToDHits[apa].size(); i++)
        fDisambigHits.push_back(fAPAToDHits[apa][i]);

    } // end loop through APA
  }

  //-------------------------------------------------
  //-------------------------------------------------
  void DisambigAlg::MakeDisambigHit(art::Ptr<recob::Hit> const& hit,
                                    geo::WireID wid,
                                    unsigned int apa)
  {
    std::pair<double, double> ChanTime(hit->Channel() * 1., hit->PeakTime() * 1.);
    if (fHasBeenDisambiged[apa][ChanTime]) return;

    if (!wid.isValid) {
      mf::LogWarning("InvalidWireID") << "wid is invalid, hit not being made\n";
      return;
    }

    fAPAToDHits[apa].emplace_back(hit, wid);
    fHasBeenDisambiged[apa][ChanTime] = true;
    fChanTimeToWid[ChanTime] = wid;
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  bool DisambigAlg::HitsOverlapInTime(detinfo::DetectorPropertiesData const& detProp,
                                      recob::Hit const& hitA,
                                      recob::Hit const& hitB)
  {
    double AsT = hitA.PeakTimeMinusRMS();
    double AeT = hitA.PeakTimePlusRMS();
    double BsT = hitB.PeakTimeMinusRMS();
    double BeT = hitB.PeakTimePlusRMS();

    if (hitA.View() == geo::kU) {
      AsT -= detProp.TimeOffsetU();
      AeT -= detProp.TimeOffsetU();
    }
    else if (hitA.View() == geo::kV) {
      AsT -= detProp.TimeOffsetV();
      AeT -= detProp.TimeOffsetV();
    }
    else if (hitA.View() == geo::kZ) {
      AsT -= detProp.TimeOffsetZ();
      AeT -= detProp.TimeOffsetZ();
    }

    if (hitB.View() == geo::kU) {
      BsT += detProp.TimeOffsetU();
      BeT -= detProp.TimeOffsetU();
    }
    else if (hitB.View() == geo::kV) {
      BsT -= detProp.TimeOffsetV();
      BeT -= detProp.TimeOffsetV();
    }
    else if (hitA.View() == geo::kZ) { // FIXME: Shouldn't this be hitB, BsT, and BeT?
      AsT -= detProp.TimeOffsetZ();
      AeT -= detProp.TimeOffsetZ();
    }

    return (AsT <= BsT && BsT <= AeT) || (AsT <= BeT && BeT <= AeT) || (BsT <= AsT && AsT <= BeT) ||
           (BsT <= AeT && AeT <= BeT);
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  void DisambigAlg::TrivialDisambig(detinfo::DetectorClocksData const& clockData,
                                    detinfo::DetectorPropertiesData const& detProp,
                                    unsigned int apa)
  {
    // Loop through ambiguous hits (U/V) in this APA
    for (auto const& hitPtr : fAPAToUVHits[apa]) {
      auto const& hit = *hitPtr;
      raw::ChannelID_t chan = hit.Channel();
      unsigned int peakT = hit.PeakTime();

      std::vector<geo::WireID> hitwids = geom->ChannelToWire(chan);
      std::vector<bool> IsReasonableWid(hitwids.size(), false);
      unsigned short nPossibleWids(0);
      for (size_t w = 0; w < hitwids.size(); w++) {
        geo::WireID wid = hitwids[w];

        double xyzStart[3] = {0.};
        double xyzEnd[3] = {0.};
        geom->WireEndPoints(wid, xyzStart, xyzEnd);
        unsigned int side(wid.TPC % 2), cryo(wid.Cryostat);
        double zminPos(xyzStart[2]), zmaxPos(xyzEnd[2]);

        // get appropriate x and y with tpc center
        unsigned int tpc =
          2 * apa + side - cryo * geom->NTPC(); // apa number does not reset per cryo
        auto const tpcCenter = geom->TPC(geo::TPCID(cryo, tpc)).GetCenter();

        // get channel range
        auto Min = tpcCenter;
        Min.SetZ(zminPos);
        auto Max = tpcCenter;
        Max.SetZ(zmaxPos);
        raw::ChannelID_t ZminChan = geom->NearestChannel(Min, geo::PlaneID{cryo, tpc, 2});
        raw::ChannelID_t ZmaxChan = geom->NearestChannel(Max, geo::PlaneID{cryo, tpc, 2});

        for (auto const& zhit : fAPAToZHits[apa] | transform(to_element)) {
          raw::ChannelID_t chan = zhit.Channel();
          if (chan <= ZminChan || ZmaxChan <= chan) continue;

          if (this->HitsOverlapInTime(detProp, hit, zhit)) {
            IsReasonableWid[w] = true;
            nPossibleWids++;
            break;
          }
        }

      } // end hit chan-wid loop

      if (nPossibleWids == 0) {
        std::vector<double> xyz;
        try {
          xyz = bt_serv->HitToXYZ(clockData, hit);
        } // TEMPORARY
        catch (...) {
          continue;
        }
        mf::LogWarning("UniqueTimeSeg")
          << "U/V hit inconsistent with Z info; peak time is " << peakT << " in APA " << apa
          << " on channel " << hit.Channel();
      }
      else if (nPossibleWids == 1) {
        for (size_t d = 0; d < hitwids.size(); d++)
          if (IsReasonableWid[d]) this->MakeDisambigHit(hitPtr, hitwids[d], apa);
      }
      else if (nPossibleWids == 2) {
      }

    } // end ambig hits loop
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  unsigned int DisambigAlg::MakeCloseHits(int ext, geo::WireID Dwid, double Dmin, double Dmax)
  {
    // Function to look, on a channel *ext* channels away from a
    // disambiguated hit channel, for hits with time windows touching
    // range *Dmin to Dmax*. If found, make such a hit to have a
    // wireID adjacent to supplied *wid*.  Returns number of NEW hits
    // made.

    raw::ChannelID_t Dchan = geom->PlaneWireToChannel(Dwid);
    geo::View_t view = geom->View(Dchan);
    if (view == geo::kZ)
      throw cet::exception("MakeCloseHits") << "Function not meant for non-wrapped channels.\n";

    // Account for wrapping
    raw::ChannelID_t firstChan = fAPAGeo.FirstChannelInView(view, Dchan);
    unsigned int ChanPerView = fAPAGeo.ChannelsInView(view);
    int tempchan = Dchan + ext; // need sign for the set of channels starting with channel 0
    if (tempchan < (int)firstChan) tempchan += ChanPerView;
    if (tempchan > (int)(firstChan + ChanPerView - 1)) tempchan -= ChanPerView;
    raw::ChannelID_t chan = (raw::ChannelID_t)(tempchan);

    // There may just be no hits
    if (fChannelToHits.count(chan) == 0) return 0;

    // There are close channel hits, so for each
    unsigned int apa(0), cryo(0);
    fAPAGeo.ChannelToAPA(chan, apa, cryo);
    unsigned int MakeCount(0);
    for (size_t i = 0; i < fChannelToHits[chan].size(); i++) {
      art::Ptr<recob::Hit> closeHit = fChannelToHits[chan][i];
      double st = closeHit->PeakTimeMinusRMS();
      double et = closeHit->PeakTimePlusRMS();
      std::vector<geo::WireID> wids = geom->ChannelToWire(chan);

      if (!(Dmin <= st && st <= Dmax) && !(Dmin <= et && et <= Dmax)) continue;

      // Found hit with window overlapping given range,
      // now find the only reasonable wireID.
      for (size_t w = 0; w < wids.size(); w++) {
        if (wids[w].TPC != Dwid.TPC) continue;
        if ((int)(wids[w].Wire) - (int)(Dwid.Wire) != ext) continue;

        // In this case, we have a unique wireID.
        // Check to see if it has already been made - if so, do not incriment count
        std::pair<double, double> ChanTime(closeHit->Channel() * 1., closeHit->PeakTime() * 1.);
        if (!fHasBeenDisambiged[apa][ChanTime]) {
          this->MakeDisambigHit(closeHit, wids[w], apa);
          MakeCount++;
          //std::cout << "     Close hit found on channel " << chan << ", time " << st<<"-"<<et << "... \n";
          //std::cout << " ... giving it wireID ("<< Dwid.Cryostat <<"," << Dwid.TPC
          //      << "," << Dwid.Plane << "," << Dwid.Wire << ")\n";
        }
        break;
      } // end find right wireID

    } // end loop through all hits on chan

    return MakeCount;
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  void DisambigAlg::Crawl(unsigned int apa)
  {

    std::vector<art::Ptr<recob::Hit>> hits = fAPAToUVHits[apa];

    // repeat this method until stable
    unsigned int nExtended(1);
    while (nExtended > 0) {
      nExtended = 0;

      // Look for any disambiguated hit ...
      for (size_t h = 0; h < hits.size(); h++) {
        std::pair<double, double> ChanTime(hits[h]->Channel() * 1., hits[h]->PeakTime() * 1.);
        if (!fHasBeenDisambiged[apa][ChanTime]) continue;
        double stD = hits[h]->PeakTimePlusRMS(-1.);
        double etD = hits[h]->PeakTimePlusRMS(+1.);
        double hitWindow = etD - stD;
        geo::WireID Dwid = fChanTimeToWid[ChanTime];

        // ... and if any neighboring-channel hits are close enough in time,
        // extend the disambiguation to the neighboring wire.
        unsigned int extensions = 0;
        for (unsigned int ext = 1; ext < fNChanJumps + 1; ext++) {
          unsigned int N(0);
          double timeExt = hitWindow * ext;
          N += this->MakeCloseHits((int)(-ext), Dwid, stD - 5 - timeExt, etD + 5 + timeExt);
          N += this->MakeCloseHits((int)(ext), Dwid, stD - 5 - timeExt, etD + 5 + timeExt);
          extensions += N;
        }
        nExtended += extensions;

      } // end UV hits loop

    } // end while still disambiguating***

    // *** nested while loops allow disambigauation to hop the channel-wrap-boundary
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  unsigned int DisambigAlg::FindChanTimeEndPts(detinfo::DetectorPropertiesData const& detProp,
                                               unsigned int apa)
  {

    double pi = 3.14159265;
    double fMaxEndPRadRange = fMaxEndPDegRange / 180. * (2 * pi);

    for (size_t h = 0; h < fAPAToHits[apa].size(); h++) {
      art::Ptr<recob::Hit> centhit = fAPAToHits[apa][h];
      geo::View_t view = centhit->View();
      unsigned int plane = 0;
      if (view == geo::kV) { plane = 1; }
      else if (view == geo::kZ)
        plane = 2;
      std::vector<double> ChanTimeCenter(2, 0.);
      unsigned int relchan = centhit->Channel() - fAPAGeo.FirstChannelInView(centhit->Channel());
      ChanTimeCenter[0] = relchan * geom->WirePitch(view);
      ChanTimeCenter[1] = detProp.ConvertTicksToX(centhit->PeakTime(),
                                                  plane,
                                                  apa * 2, // tpc doesnt matter
                                                  centhit->WireID().Cryostat);
      //std::vector< art::Ptr<recob::Hit> > CloseHits;
      std::vector<std::vector<double>> CloseHitsChanTime;
      std::vector<double> FurthestCloseChanTime(2, 0.); //double maxDist = 0.;
      std::vector<double> ClosestChanTime(2, 0.);
      double minDist = fCloseHitsRadius + 1.;
      double ChanDistRange = fAPAGeo.ChannelsInView(view) * geom->WirePitch(view);

      for (size_t c = 0; c < fAPAToHits[apa].size(); c++) {
        art::Ptr<recob::Hit> closehit = fAPAToHits[apa][c];
        if (view != closehit->View()) continue;
        if (view == geo::kZ && centhit->WireID().TPC != closehit->WireID().TPC) continue;
        unsigned int plane = 0;
        if (view == geo::kV) { plane = 1; }
        else if (view == geo::kZ)
          plane = 2;
        std::vector<double> ChanTimeClose(2, 0.);
        unsigned int relchanclose =
          closehit->Channel() - fAPAGeo.FirstChannelInView(closehit->Channel());
        ChanTimeClose[0] = relchanclose * geom->WirePitch(view);
        ChanTimeClose[1] = detProp.ConvertTicksToX(closehit->PeakTime(),
                                                   plane,
                                                   apa * 2, // tpc doesnt matter
                                                   closehit->WireID().Cryostat);
        if (ChanTimeClose == ChanTimeCenter) continue; // move on if the same one

        double ChanDist = ChanTimeClose[0] - ChanTimeCenter[0];
        if (ChanDist > ChanDistRange / 2) ChanDist = ChanDistRange - ChanDist;

        double distance = std::hypot(ChanDist, ChanTimeClose[1] - ChanTimeCenter[1]);

        if (distance <= fCloseHitsRadius) CloseHitsChanTime.push_back(ChanTimeClose);

        if (distance < minDist) {
          ClosestChanTime = ChanTimeClose;
          minDist = distance;
        }

      } // end close-by hit loop

      if (CloseHitsChanTime.size() < 5) continue; // quick fix, to-be improved

      double minRad(2 * pi + 1.), maxRad(0.);
      bool CloseToNegPi(false), CloseToPosPi(false);
      for (size_t i = 0; i < CloseHitsChanTime.size(); i++) {
        std::vector<double> ThisChanTime(CloseHitsChanTime[i]);
        //if(ThisChanTime==ClosestChanTime) continue;
        double ChanDist = ThisChanTime[0] - ChanTimeCenter[0];
        if (ChanDist > ChanDistRange / 2) ChanDist = ChanDistRange - ChanDist;
        double hitrad = std::atan2(ThisChanTime[1] - ChanTimeCenter[1], ChanDist);
        if (hitrad > maxRad) maxRad = hitrad;
        if (hitrad < minRad) minRad = hitrad;
        if (hitrad + fMaxEndPRadRange > pi)
          CloseToPosPi = true;
        else if (hitrad - fMaxEndPRadRange < -pi)
          CloseToNegPi = true;
      }

      // activity at this boundary automatically kills the test, move boundary and redo
      if (CloseToPosPi && CloseToNegPi) {
        for (size_t i = 0; i < CloseHitsChanTime.size(); i++) {
          std::vector<double> ThisChanTime(CloseHitsChanTime[i]);
          //if(ThisChanTime==ClosestChanTime) continue;
          double ChanDist = ThisChanTime[0] - ChanTimeCenter[0];
          if (ChanDist > ChanDistRange / 2) ChanDist = ChanDistRange - ChanDist;
          double hitrad = std::atan2(ThisChanTime[1] - ChanTimeCenter[1], ChanDist);
          if (hitrad > 0) hitrad = pi - hitrad; // reflec across pi/2 line
          if (hitrad < 0) hitrad = -pi - hitrad;
          if (hitrad > maxRad) maxRad = hitrad;
          if (hitrad < minRad) minRad = hitrad;
        }
      }

      if (maxRad - minRad < fMaxEndPRadRange) fAPAToEndPHits[apa].push_back(centhit);

    } // end UV hit loop

    if (fAPAToEndPHits[apa].size() == 0) return 0;
    mf::LogVerbatim("FindChanTimeEndPts") << "          Found " << fAPAToEndPHits[apa].size()
                                          << " endpoint hits in apa " << apa << std::endl;
    for (size_t ep = 0; ep < fAPAToEndPHits[apa].size(); ep++) {
      art::Ptr<recob::Hit> epHit = fAPAToEndPHits[apa][ep];
      mf::LogVerbatim("FindChanTimeEndPts") << "           endP on channel " << epHit->Channel()
                                            << " at time " << epHit->PeakTime() << std::endl;
    }

    return fAPAToEndPHits[apa].size();
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  void DisambigAlg::UseEndPts(detinfo::DetectorPropertiesData const& detProp, unsigned int apa)
  {


    if (fAPAToEndPHits[apa].size() == 0) {
      mf::LogVerbatim("UseEndPts") << "          APA " << apa << " has no endpoints.";
      return;
    }
    std::vector<art::Ptr<recob::Hit>> const& endPts = fAPAToEndPHits[apa];

    std::vector<std::vector<art::Ptr<recob::Hit>>> EndPMatch;
    unsigned short nZendPts(0);

    auto on_z_plane = [](art::Ptr<recob::Hit> const& hit) { return hit->View() == geo::kZ; };
    auto not_on_z_plane = [](art::Ptr<recob::Hit> const& hit) { return hit->View() != geo::kZ; };
    for (auto const& ZHitPtr : endPts | filter(on_z_plane)) {
      auto const& ZHit = *ZHitPtr;
      art::Ptr<recob::Hit> Uhit = ZHitPtr;
      art::Ptr<recob::Hit> Vhit = ZHitPtr;
      unsigned short Umatch(0), Vmatch(0);
      ++nZendPts;

      // look for U and V hits overlapping in time
      for (auto const& hitPtr : endPts | filter(not_on_z_plane)) {
        auto const& hit = *hitPtr;
        if (not HitsOverlapInTime(detProp, ZHit, hit)) continue;

        if (hit.View() == geo::kU) {
          Uhit = hitPtr;
          Umatch++;
        }
        else if (hit.View() == geo::kV) {
          Vhit = hitPtr;
          Vmatch++;
        }
      }

      unsigned int tpc(ZHit.WireID().TPC), cryo(ZHit.WireID().Cryostat);
      auto const tpcCenter = geom->TPC(geo::TPCID{cryo, tpc}).GetCenter();

      if (Umatch == 1 && Vmatch == 1) {

        std::vector<double> yzEndPt =
          fAPAGeo.ThreeChanPos(Uhit->Channel(), Vhit->Channel(), ZHit.Channel());
        double intersect[3] = {tpcCenter.X(), yzEndPt[0], yzEndPt[1]};

        geo::WireID Uwid = fAPAGeo.NearestWireIDOnChan(intersect, Uhit->Channel(), 0, tpc, cryo);
        geo::WireID Vwid = fAPAGeo.NearestWireIDOnChan(intersect, Vhit->Channel(), 1, tpc, cryo);
        this->MakeDisambigHit(Uhit, Uwid, apa);
        this->MakeDisambigHit(Vhit, Vwid, apa);
      }
      else if (Umatch == 1 && Vmatch != 1) {

        std::vector<geo::WireIDIntersection> widIntersects;
        fAPAGeo.APAChannelsIntersect(Uhit->Channel(), ZHit.Channel(), widIntersects);
        if (widIntersects.size() == 0)
          continue;
        else if (widIntersects.size() == 1) {
          double intersect[3] = {tpcCenter.X(), widIntersects[0].y, widIntersects[0].z};
          geo::WireID Uwid = fAPAGeo.NearestWireIDOnChan(intersect, Uhit->Channel(), 0, tpc, cryo);
          this->MakeDisambigHit(Uhit, Uwid, apa);
        }
        else {
          for (size_t i = 0; i < widIntersects.size(); i++) {
            // compare to V hit times, see if only one makes sense
          }
        }
      }
      else if (Umatch == 1 && Vmatch != 1) {

        std::vector<geo::WireIDIntersection> widIntersects;
        fAPAGeo.APAChannelsIntersect(Vhit->Channel(), ZHit.Channel(), widIntersects);
        if (widIntersects.size() == 0)
          continue;
        else if (widIntersects.size() == 1) {
          double intersect[3] = {tpcCenter.X(), widIntersects[0].y, widIntersects[0].z};
          geo::WireID Vwid = fAPAGeo.NearestWireIDOnChan(intersect, Vhit->Channel(), 0, tpc, cryo);
          this->MakeDisambigHit(Vhit, Vwid, apa);
        }
      }
    }

    if (nZendPts == 0 && endPts.size() == 2 &&
        this->HitsOverlapInTime(detProp, *endPts[0], *endPts[1])) {
      std::vector<geo::WireIDIntersection> widIntersects;
      fAPAGeo.APAChannelsIntersect(endPts[0]->Channel(), endPts[1]->Channel(), widIntersects);
      if (widIntersects.size() == 1) {
        unsigned int cryo = endPts[0]->WireID().Cryostat;
        unsigned int tpc = widIntersects[0].TPC;
        auto const tpcCenter = geom->TPC(geo::TPCID(cryo, tpc)).GetCenter();
        double intersect[3] = {tpcCenter.X(), widIntersects[0].y, widIntersects[0].z};
        unsigned int plane0(0), plane1(0);
        if (endPts[0]->View() == geo::kV) plane0 = 1;
        if (endPts[1]->View() == geo::kV) plane1 = 1;
        geo::WireID wid0 =
          fAPAGeo.NearestWireIDOnChan(intersect, endPts[0]->Channel(), plane0, tpc, cryo);
        this->MakeDisambigHit(endPts[0], wid0, apa);
        geo::WireID wid1 =
          fAPAGeo.NearestWireIDOnChan(intersect, endPts[1]->Channel(), plane1, tpc, cryo);
        this->MakeDisambigHit(endPts[1], wid1, apa);
      }
    }

    this->Crawl(apa);
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  void DisambigAlg::AssessDisambigSoFar(unsigned int apa)
  {
    unsigned int nU(0), nV(0);
    for (size_t h = 0; h < fAPAToUVHits[apa].size(); h++) {
      art::Ptr<recob::Hit> hit = fAPAToUVHits[apa][h];
      if (hit->View() == geo::kU)
        nU++;
      else if (hit->View() == geo::kV)
        nV++;
    }

    unsigned int nDU(0), nDV(0);
    for (size_t h = 0; h < fAPAToDHits[apa].size(); h++) {
      art::Ptr<recob::Hit> hit = fAPAToDHits[apa][h].first;
      if (hit->View() == geo::kU)
        nDU++;
      else if (hit->View() == geo::kV)
        nDV++;
    }

    fUeffSoFar[apa] = (nDU * 1.) / (nU * 1.);
    fVeffSoFar[apa] = (nDV * 1.) / (nV * 1.);
    fnUSoFar[apa] = nU;
    fnVSoFar[apa] = nV;
    fnDUSoFar[apa] = nDU;
    fnDVSoFar[apa] = nDV;
  }

  //----------------------------------------------------------
  //----------------------------------------------------------
  unsigned int DisambigAlg::CompareViews(detinfo::DetectorPropertiesData const& detProp,
                                         unsigned int apa)
  {
    unsigned int nDisambiguations(0);

    // loop through all hits that are still ambiguous
    for (auto const& ambighitPtr : fAPAToUVHits[apa]) {
      auto const& ambighit = *ambighitPtr;
      raw::ChannelID_t ambigchan = ambighit.Channel();
      std::pair<double, double> ambigChanTime(ambigchan * 1., ambighit.PeakTime());
      if (fHasBeenDisambiged[apa][ambigChanTime]) continue;
      geo::View_t view = ambighit.View();
      std::vector<geo::WireID> ambigwids = geom->ChannelToWire(ambigchan);
      std::vector<unsigned int> widDcounts(ambigwids.size(), 0);
      std::vector<unsigned int> widAcounts(ambigwids.size(), 0);

      // loop through hits in the other view which are close in time
      for (auto const& hit : fAPAToUVHits[apa] | transform(to_element)) {
        if (hit.View() == view || !this->HitsOverlapInTime(detProp, ambighit, hit)) continue;

        // An other-view-hit overlaps in time, see what
        // wids of the ambiguous hit's channels it overlaps
        raw::ChannelID_t chan = hit.Channel();
        std::vector<geo::WireID> wids = geom->ChannelToWire(chan);
        std::pair<double, double> ChanTime(chan * 1., hit.PeakTime());
        geo::WireIDIntersection widIntersect; // only so we can use the function
        if (fHasBeenDisambiged[apa][ChanTime]) {
          for (size_t a = 0; a < ambigwids.size(); a++)
            if (ambigwids[a].TPC == fChanTimeToWid[ChanTime].TPC &&
                geom->WireIDsIntersect(ambigwids[a], fChanTimeToWid[ChanTime], widIntersect))
              widDcounts[a]++;
        }
        else {
          // still might be able to glean disambiguation
          // from the ambiguous hits at this time
          for (size_t a = 0; a < ambigwids.size(); a++)
            for (size_t w = 0; w < wids.size(); w++)
              if (ambigwids[a].TPC == wids[w].TPC &&
                  geom->WireIDsIntersect(ambigwids[a], wids[w], widIntersect))
                widAcounts[a]++;
        }
      } // end loop through close-time hits

      // For now, just make a hit if either ambig or disambig hits
      // unanimously intersect a single wireID
      unsigned int Dcount(0), Acount(0);
      for (size_t d = 0; d < widDcounts.size(); d++)
        Dcount += widDcounts[d];
      for (size_t a = 0; a < widAcounts.size(); a++)
        Acount += widAcounts[a];
      for (size_t d = 0; d < widDcounts.size(); d++) {
        if (Dcount == widDcounts[d] && Dcount > 0 && Acount == 0) {
          this->MakeDisambigHit(ambighitPtr, ambigwids[d], apa);
          nDisambiguations++;
        }
      }
    } // end loop through still ambiguous hits

    return nDisambiguations;
  }

} //end namespace apa