ClusterSequence.hh

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// $Id: ClusterSequence.hh 329 2006-10-09 12:29:46Z salam $
//
// Copyright (c) 2005-2006, Matteo Cacciari and Gavin Salam
//
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// This file is part of FastJet.
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//  FastJet is free software; you can redistribute it and/or modify
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//----------------------------------------------------------------------
// here's where we put the main page for fastjet (as explained in the
// Doxygen faq)
//......................................................................
//----------------------------------------------------------------------

#ifndef __FASTJET_CLUSTERSEQUENCE_HH__
#define __FASTJET_CLUSTERSEQUENCE_HH__

#include<vector>
#include<map>
#include "fastjet/internal/DynamicNearestNeighbours.hh"
#include "fastjet/PseudoJet.hh"
#include<cassert>
#include<iostream>
#include<string>
#include<cmath> // needed to get double std::abs(double)
#include "fastjet/Error.hh"
#include "fastjet/JetDefinition.hh"

FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh


class ClusterSequence {


 public: 

  ClusterSequence () {};

  template<class L> ClusterSequence (const std::vector<L> & pseudojets, 
                   const double & R = 1.0,
                   const Strategy & strategy = Best,
                   const bool & writeout_combinations = false);


  template<class L> ClusterSequence (
                                  const std::vector<L> & pseudojets,
                                  const JetDefinition & jet_def,
                                  const bool & writeout_combinations = false);


  // NB: in the routines that follow, for extracting lists of jets, a
  //     list structure might be more efficient, if sometimes a little
  //     more awkward to use (at least for old fortran hands).

  std::vector<PseudoJet> inclusive_jets (const double & ptmin = 0.0) const;

  int n_exclusive_jets (const double & dcut) const;

  std::vector<PseudoJet> exclusive_jets (const double & dcut) const;

  std::vector<PseudoJet> exclusive_jets (const int & njets) const;

  double exclusive_dmerge (const int & njets) const;

  double exclusive_dmerge_max (const int & njets) const;

  std::vector<PseudoJet> constituents (const PseudoJet & jet) const;
  void add_constituents (const PseudoJet & jet, 
                         std::vector<PseudoJet> & subjet_vector) const;

  inline Strategy strategy_used () const {return _strategy;};
  std::string strategy_string () const;


  double jet_scale_for_algorithm(const PseudoJet & jet) const;

//  /// things related to choice of algorithm
//  enum JetFinder { kt_algorithm = 0, cambridge_algorithm = 1};
//

public:
  static void set_jet_finder (JetFinder jet_finder) {_default_jet_finder = jet_finder;};


  struct history_element{
    int parent1; 



    int parent2; 





    int child;   




    int jetp_index; 






    double dij;  


    double max_dij_so_far; 

  };

  enum JetType {Invalid=-3, InexistentParent = -2, BeamJet = -1};

  const std::vector<PseudoJet> & jets()    const;

  const std::vector<history_element> & history() const;

  unsigned int n_particles() const;


  std::vector<int> unique_history_order() const;


protected:
  static JetFinder _default_jet_finder;
  JetDefinition _jet_def;

  template<class L> void _transfer_input_jets(
                                     const std::vector<L> & pseudojets);

  void _initialise_and_run (const JetDefinition & jet_def,
                            const bool & writeout_combinations);

  void _initialise_and_run (const double & R,
                            const Strategy & strategy,
                            const bool & writeout_combinations);

  void _decant_options(const JetDefinition & jet_def,
                       const bool & writeout_combinations);

  void _fill_initial_history();

  void _do_ij_recombination_step(const int & jet_i, const int & jet_j, 
                                 const double & dij, int & newjet_k);

  void _do_iB_recombination_step(const int & jet_i, const double & diB);


  std::vector<PseudoJet> _jets;


  std::vector<history_element> _history;

  bool _writeout_combinations;
  int  _initial_n;
  double _Rparam, _R2, _invR2;
  Strategy    _strategy;
  JetFinder   _jet_finder;

 private:


  void _really_dumb_cluster ();
  void _delaunay_cluster ();
  void _simple_N2_cluster ();
  void _tiled_N2_cluster ();
  void _faster_tiled_N2_cluster ();

  //
  void _minheap_faster_tiled_N2_cluster();

  // things needed specifically for Cambridge with Chan's 2D closest
  // pairs method
  void _CP2DChan_cluster();
  void _CP2DChan_cluster_2pi2R ();
  void _CP2DChan_cluster_2piMultD ();
  void _CP2DChan_limited_cluster(double D);
  void _do_Cambridge_inclusive_jets();

  void _add_step_to_history(const int & step_number, const int & parent1, 
                               const int & parent2, const int & jetp_index,
                               const double & dij);

  void _extract_tree_children(int pos, std::valarray<bool> &, 
                const std::valarray<int> &, std::vector<int> &) const;

  void _extract_tree_parents (int pos, std::valarray<bool> &, 
                const std::valarray<int> &,  std::vector<int> &) const;


  // these will be useful shorthands in the Voronoi-based code
  typedef std::pair<int,int> TwoVertices;
  typedef std::pair<double,TwoVertices> DijEntry;
  typedef std::multimap<double,TwoVertices> DistMap;

  void _add_ktdistance_to_map(const int & ii, 
                              DistMap & DijMap,
                              const DynamicNearestNeighbours * DNN);

  void _print_banner();
  static bool _first_time;


  //----------------------------------------------------------------------
  struct BriefJet {
    double     eta, phi, kt2, NN_dist;
    BriefJet * NN;
    int        _jets_index;
  };
  class TiledJet {
  public:
    double     eta, phi, kt2, NN_dist;
    TiledJet * NN, *previous, * next; 
    int        _jets_index, tile_index, diJ_posn;
    // routines that are useful in the minheap version of tiled
    // clustering ("misuse" the otherwise unused diJ_posn, so as
    // to indicate whether jets need to have their minheap entries
    // updated).
    inline void label_minheap_update_needed() {diJ_posn = 1;};
    inline void label_minheap_update_done()   {diJ_posn = 0;};
    inline bool minheap_update_needed() const {return diJ_posn==1;};
  };

  //-- some of the functions that follow are templates and will work
  //as well for briefjet and tiled jets

  template <class J> void _bj_set_jetinfo( J * const jet, 
                                                 const int _jets_index) const;

  void _bj_remove_from_tiles( TiledJet * const jet) const;

  template <class J> double _bj_dist(const J * const jeta, 
                        const J * const jetb) const;

  // return the diJ (multiplied by _R2) for this jet assuming its NN
  // info is correct
  template <class J> double _bj_diJ(const J * const jeta) const;

  template <class J> inline J * _bj_of_hindex(
                          const int hist_index, 
                          J * const head, J * const tail) 
    const {
    J * res;
    for(res = head; res<tail; res++) {
      if (_jets[res->_jets_index].cluster_hist_index() == hist_index) {break;}
    }
    return res;
  };


  //-- remaining functions are different in various cases, so we
  //   will use templates but are not sure if they're useful...

  template <class J> void _bj_set_NN_nocross(J * const jeta, 
            J * const head, const J * const tail) const;

  template <class J> void _bj_set_NN_crosscheck(J * const jeta, 
            J * const head, const J * const tail) const;
  


  static const int n_tile_neighbours = 9;
  //----------------------------------------------------------------------
  struct Tile {
    Tile *   begin_tiles[n_tile_neighbours]; 
    Tile **  surrounding_tiles; 
    Tile **  RH_tiles;  
    Tile **  end_tiles; 
    TiledJet * head;    
    bool     tagged;    
  };
  std::vector<Tile> _tiles;
  double _tiles_eta_min, _tiles_eta_max;
  double _tile_size_eta, _tile_size_phi;
  int    _n_tiles_phi,_tiles_ieta_min,_tiles_ieta_max;

  // reasonably robust return of tile index given ieta and iphi, in particular
  // it works even if iphi is negative
  inline int _tile_index (int ieta, int iphi) const {
    // note that (-1)%n = -1 so that we have to add _n_tiles_phi
    // before performing modulo operation
    return (ieta-_tiles_ieta_min)*_n_tiles_phi
                  + (iphi+_n_tiles_phi) % _n_tiles_phi;
  }

  // routines for tiled case, including some overloads of the plain
  // BriefJet cases
  int  _tile_index(const double & eta, const double & phi) const;
  void _tj_set_jetinfo ( TiledJet * const jet, const int _jets_index);
  void  _bj_remove_from_tiles(TiledJet * const jet);
  void _initialise_tiles();
  void _print_tiles(TiledJet * briefjets ) const;
  void _add_neighbours_to_tile_union(const int tile_index, 
                 std::vector<int> & tile_union, int & n_near_tiles) const;
  void _add_untagged_neighbours_to_tile_union(const int tile_index, 
                 std::vector<int> & tile_union, int & n_near_tiles);


};



//**********************************************************************
//**************    START   OF   INLINE   MATERIAL    ******************
//**********************************************************************


//----------------------------------------------------------------------
// Transfer the initial jets into our internal structure
template<class L> void ClusterSequence::_transfer_input_jets(
                                       const std::vector<L> & pseudojets) {

  // this will ensure that we can point to jets without difficulties
  // arising.
  _jets.reserve(pseudojets.size()*2);

  // insert initial jets this way so that any type L that can be
  // converted to a pseudojet will work fine (basically PseudoJet
  // and any type that has [] subscript access to the momentum
  // components, such as CLHEP HepLorentzVector).
  for (unsigned int i = 0; i < pseudojets.size(); i++) {
    _jets.push_back(pseudojets[i]);}
  
}

//----------------------------------------------------------------------
// initialise from some generic type... Has to be made available
// here in order for it the template aspect of it to work...
template<class L> ClusterSequence::ClusterSequence (
                                  const std::vector<L> & pseudojets,
                                  const double & R,
                                  const Strategy & strategy,
                                  const bool & writeout_combinations) {

  // transfer the initial jets (type L) into our own array
  _transfer_input_jets(pseudojets);

  // run the clustering
  _initialise_and_run(R,strategy,writeout_combinations);
}


//----------------------------------------------------------------------
template<class L> ClusterSequence::ClusterSequence (
                                  const std::vector<L> & pseudojets,
                                  const JetDefinition & jet_def,
                                  const bool & writeout_combinations) {

  // transfer the initial jets (type L) into our own array
  _transfer_input_jets(pseudojets);

  // run the clustering
  _initialise_and_run(jet_def,writeout_combinations);
}


inline const std::vector<PseudoJet> & ClusterSequence::jets () const {
  return _jets;
}

inline const std::vector<ClusterSequence::history_element> & ClusterSequence::history () const {
  return _history;
}

inline unsigned int ClusterSequence::n_particles() const {return _initial_n;}



inline double ClusterSequence::jet_scale_for_algorithm(
                                  const PseudoJet & jet) const {
  if (_jet_finder == kt_algorithm)             {return jet.kt2();}
  else if (_jet_finder == cambridge_algorithm) {return 1.0;}
  else {throw Error("Unrecognised jet finder");}
}


//----------------------------------------------------------------------
template <class J> inline void ClusterSequence::_bj_set_jetinfo(
                            J * const jetA, const int _jets_index) const {
    jetA->eta  = _jets[_jets_index].rap();
    jetA->phi  = _jets[_jets_index].phi_02pi();
    jetA->kt2  = jet_scale_for_algorithm(_jets[_jets_index]);
    jetA->_jets_index = _jets_index;
    // initialise NN info as well
    jetA->NN_dist = _R2;
    jetA->NN      = NULL;
}




//----------------------------------------------------------------------
template <class J> inline double ClusterSequence::_bj_dist(
                const J * const jetA, const J * const jetB) const {
  double dphi = std::abs(jetA->phi - jetB->phi);
  double deta = (jetA->eta - jetB->eta);
  if (dphi > pi) {dphi = twopi - dphi;}
  return dphi*dphi + deta*deta;
}

//----------------------------------------------------------------------
template <class J> inline double ClusterSequence::_bj_diJ(const J * const jet) const {
  double kt2 = jet->kt2;
  if (jet->NN != NULL) {if (jet->NN->kt2 < kt2) {kt2 = jet->NN->kt2;}}
  return jet->NN_dist * kt2;
}


//----------------------------------------------------------------------
// set the NN for jet without checking whether in the process you might
// have discovered a new nearest neighbour for another jet
template <class J> inline void ClusterSequence::_bj_set_NN_nocross(
                 J * const jet, J * const head, const J * const tail) const {
  double NN_dist = _R2;
  J * NN  = NULL;
  if (head < jet) {
    for (J * jetB = head; jetB != jet; jetB++) {
      double dist = _bj_dist(jet,jetB);
      if (dist < NN_dist) {
        NN_dist = dist;
        NN = jetB;
      }
    }
  }
  if (tail > jet) {
    for (J * jetB = jet+1; jetB != tail; jetB++) {
      double dist = _bj_dist(jet,jetB);
      if (dist < NN_dist) {
        NN_dist = dist;
        NN = jetB;
      }
    }
  }
  jet->NN = NN;
  jet->NN_dist = NN_dist;
}


//----------------------------------------------------------------------
template <class J> inline void ClusterSequence::_bj_set_NN_crosscheck(J * const jet, 
                    J * const head, const J * const tail) const {
  double NN_dist = _R2;
  J * NN  = NULL;
  for (J * jetB = head; jetB != tail; jetB++) {
    double dist = _bj_dist(jet,jetB);
    if (dist < NN_dist) {
      NN_dist = dist;
      NN = jetB;
    }
    if (dist < jetB->NN_dist) {
      jetB->NN_dist = dist;
      jetB->NN = jet;
    }
  }
  jet->NN = NN;
  jet->NN_dist = NN_dist;
}




FASTJET_END_NAMESPACE

#endif // __FASTJET_CLUSTERSEQUENCE_HH__

---