ClusterSequenceStructure.hh

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//
// Copyright (c) 2005-2026, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
//
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// This file is part of FastJet.
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#ifndef __FASTJET_CLUSTER_SEQUENCE_STRUCTURE_HH__
#define __FASTJET_CLUSTER_SEQUENCE_STRUCTURE_HH__
 
#include "fastjet/internal/base.hh"
#include "fastjet/SharedPtr.hh"
#include "fastjet/PseudoJetStructureBase.hh"
 
#include <vector>
 
FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh
 
/// @ingroup extra_info
/// \class ClusterSequenceStructure
///
/// Contains any information related to the clustering that should be
/// directly accessible to PseudoJet.
///
/// By default, this class implements basic access to the
/// ClusterSequence related to a PseudoJet (like its constituents or
/// its area). But it can be overloaded in order e.g. to give access
/// to the jet substructure.
///
// Design question: Do we only put the methods that can be overloaded
// or do we put everything a PJ can have access to? I think both cost
// the same number of indirections. The first option limits the amount
// of coding and maybe has a clearer structure. The second is more
// consistent (everything related to the same thing is at the same
// place) and gives better access for derived classes. We'll go for
// the second option.
class ClusterSequenceStructure : public PseudoJetStructureBase{
public:
  /// default ctor
  ClusterSequenceStructure() : _associated_cs(NULL){}
 
  /// ctor with initialisation to a given ClusterSequence
  /// 
  /// In principle, this is reserved for initialisation by the parent
  /// ClusterSequence
  ClusterSequenceStructure(const ClusterSequence *cs){
    set_associated_cs(cs);
  };
 
  /// default (virtual) dtor
  virtual ~ClusterSequenceStructure();
 
  /// description
  virtual std::string description() const FASTJET_OVERRIDE{
    return "PseudoJet with an associated ClusterSequence";
  }
 
  //-------------------------------------------------------------
  /// @name Direct access to the associated ClusterSequence object.
  ///
  /// Get access to the associated ClusterSequence (if any)
  //\{
  //-------------------------------------------------------------
  /// returns true if there is an associated ClusterSequence
  virtual bool has_associated_cluster_sequence() const FASTJET_OVERRIDE{ return true;}
 
  /// get a (const) pointer to the parent ClusterSequence (NULL if
  /// inexistent)
  virtual const ClusterSequence* associated_cluster_sequence() const FASTJET_OVERRIDE;
  
  /// returns true if there is a valid associated ClusterSequence
  virtual bool has_valid_cluster_sequence() const FASTJET_OVERRIDE;
 
  /// if the jet has a valid associated cluster sequence then return a
  /// pointer to it; otherwise throw an error
  virtual const ClusterSequence * validated_cs() const FASTJET_OVERRIDE;
 
#ifndef __FASTJET_ONLY_CORE__
  /// if the jet has valid area information then return a pointer to
  /// the associated ClusterSequenceAreaBase object; otherwise throw an error
  virtual const ClusterSequenceAreaBase * validated_csab() const FASTJET_OVERRIDE;
#endif  // __FASTJET_ONLY_CORE__
 
  /// set the associated csw
  virtual void set_associated_cs(const ClusterSequence * new_cs){
    _associated_cs = new_cs;
  }
  //\}
 
  //-------------------------------------------------------------
  /// @name Methods for access to information about jet structure
  ///
  /// These allow access to jet constituents, and other jet
  /// subtructure information. They only work if the jet is associated
  /// with a ClusterSequence.
  //-------------------------------------------------------------
  //\{
 
  /// check if it has been recombined with another PseudoJet in which
  /// case, return its partner through the argument. Otherwise,
  /// 'partner' is set to 0.
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual bool has_partner(const PseudoJet &reference, PseudoJet &partner) const FASTJET_OVERRIDE;
 
  /// check if it has been recombined with another PseudoJet in which
  /// case, return its child through the argument. Otherwise, 'child'
  /// is set to 0.
  /// 
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual bool has_child(const PseudoJet &reference, PseudoJet &child) const FASTJET_OVERRIDE;
 
  /// check if it is the product of a recombination, in which case
  /// return the 2 parents through the 'parent1' and 'parent2'
  /// arguments. Otherwise, set these to 0.
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual bool has_parents(const PseudoJet &reference, PseudoJet &parent1, PseudoJet &parent2) const FASTJET_OVERRIDE;
 
  /// check if the reference PseudoJet is contained in the second one
  /// passed as argument.
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  ///
  /// false is returned if the 2 PseudoJet do not belong the same
  /// ClusterSequence
  virtual bool object_in_jet(const PseudoJet &reference, const PseudoJet &jet) const FASTJET_OVERRIDE;
 
  /// return true if the structure supports constituents. 
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual bool has_constituents() const FASTJET_OVERRIDE;
 
  /// retrieve the constituents. 
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual std::vector<PseudoJet> constituents(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
 
  /// return true if the structure supports exclusive_subjets. 
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual bool has_exclusive_subjets() const FASTJET_OVERRIDE;
 
  /// return a vector of all subjets of the current jet (in the sense
  /// of the exclusive algorithm) that would be obtained when running
  /// the algorithm with the given dcut. 
  ///
  /// Time taken is O(m ln m), where m is the number of subjets that
  /// are found. If m gets to be of order of the total number of
  /// constituents in the jet, this could be substantially slower than
  /// just getting that list of constituents.
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual std::vector<PseudoJet> exclusive_subjets(const PseudoJet &reference, const double & dcut) const FASTJET_OVERRIDE;
 
  /// return the size of exclusive_subjets(...); still n ln n with same
  /// coefficient, but marginally more efficient than manually taking
  /// exclusive_subjets.size()
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual int n_exclusive_subjets(const PseudoJet &reference, const double & dcut) const FASTJET_OVERRIDE;
 
  /// return the list of subjets obtained by unclustering the supplied
  /// jet down to nsub subjets (or all constituents if there are fewer
  /// than nsub).
  ///
  /// requires nsub ln nsub time
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual std::vector<PseudoJet> exclusive_subjets_up_to (const PseudoJet &reference, int nsub) const FASTJET_OVERRIDE;
 
  /// return the dij that was present in the merging nsub+1 -> nsub 
  /// subjets inside this jet.
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual double exclusive_subdmerge(const PseudoJet &reference, int nsub) const FASTJET_OVERRIDE;
 
  /// return the maximum dij that occurred in the whole event at the
  /// stage that the nsub+1 -> nsub merge of subjets occurred inside 
  /// this jet.
  ///
  /// an Error is thrown if this PseudoJet has no currently valid
  /// associated ClusterSequence
  virtual double exclusive_subdmerge_max(const PseudoJet &reference, int nsub) const FASTJET_OVERRIDE;
 
 
  //-------------------------------------------------------------------
  // information related to the pieces of the jet
  //-------------------------------------------------------------------
  /// by convention, a jet associated with a ClusterSequence will have
  /// its parents as pieces
  virtual bool has_pieces(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
  /// by convention, a jet associated with a ClusterSequence will have
  /// its parents as pieces
  ///
  /// if it has no parents, then there will only be a single piece:
  /// itself
  ///
  /// Note that to answer that question, we need to access the cluster
  /// sequence. If the cluster sequence has gone out of scope, an
  /// error will be thrown
  virtual std::vector<PseudoJet> pieces(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
 
  // the following ones require a computation of the area in the
  // parent ClusterSequence (See ClusterSequenceAreaBase for details)
  //------------------------------------------------------------------
#ifndef __FASTJET_ONLY_CORE__
 
  /// check if it has a defined area
  virtual bool has_area() const FASTJET_OVERRIDE;
 
  /// return the jet (scalar) area.
  /// throws an Error if there is no support for area in the parent CS
  virtual double area(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
  /// return the error (uncertainty) associated with the determination
  /// of the area of this jet.
  /// throws an Error if there is no support for area in the parent CS
  virtual double area_error(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
  /// return the jet 4-vector area.
  /// throws an Error if there is no support for area in the parent CS
  virtual PseudoJet area_4vector(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
  /// true if this jet is made exclusively of ghosts.
  /// throws an Error if there is no support for area in the parent CS
  virtual bool is_pure_ghost(const PseudoJet &reference) const FASTJET_OVERRIDE;
 
#endif  // __FASTJET_ONLY_CORE__
  //\} --- end of jet structure -------------------------------------
 
protected:
  const ClusterSequence *_associated_cs;
};
 
FASTJET_END_NAMESPACE
 
#endif  //  __FASTJET_CLUSTER_SEQUENCE_STRUCTURE_HH__