ZiggZaggRZ.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#pragma once
 
#include <tracking/trackFindingVXD/filterMap/filterFramework/SelectionVariable.h>
#include <tracking/trackFindingVXD/filterTools/SelectionVariableHelper.h>
#include <framework/geometry/B2Vector3.h>
#include <boost/math/special_functions/sign.hpp>
 
#include <vector>
#include <algorithm>
 
 
#define ZIGGZAGGRZ_NAME ZiggZaggRZ
 
namespace Belle2 {
  template <typename PointType, typename PointContainerType >
  class ZIGGZAGGRZ_NAME : public SelectionVariable< PointContainerType, 0, int > {
  public:
    PUT_NAME_FUNCTION(ZIGGZAGGRZ_NAME);
 
 
    static int value(const PointContainerType& hitContainer)
    {
      const unsigned nHits = hitContainer.size();
      if (nHits < 4) return 1;
 
      typedef SelVarHelper<PointType, double> Helper;
      using boost::math::sign;
 
      std::vector<B2Vector3D> vecRZ;
      vecRZ.reserve(nHits);
      for (const auto* hit : hitContainer) { // collect RZ-Vrsions of the hits:
        vecRZ.push_back(B2Vector3D(Helper::calcPerp(*hit), hit->Z(), 0.));
      }
 
      std::vector<int> chargeSigns;
      chargeSigns.reserve(nHits - 2);
      for (unsigned i = 0; i < nHits - 2; ++i) {
        int signVal = sign((vecRZ.at(i + 1) - vecRZ.at(i + 2)).Orthogonal() * (vecRZ.at(i) - vecRZ.at(i + 1)));
        chargeSigns.push_back(signVal);
      }
 
      std::sort(chargeSigns.begin(), chargeSigns.end());
      auto newEnd = std::unique(chargeSigns.begin(), chargeSigns.end());
 
      return std::distance(chargeSigns.begin(), newEnd);
    } // return unit: none
  };
 
}