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 #ifndef __FASTJET_CONTRIB_TOOLS_RECLUSTER_HH__
 #define __FASTJET_CONTRIB_TOOLS_RECLUSTER_HH__
 
 // $Id: Recluster.hh 1444 2024-12-09 18:15:56Z salam $
 //
 // Copyright (c) 2014-, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
 //
 //----------------------------------------------------------------------
 // This file is part of FastJet contrib.
 //
 // It is free software; you can redistribute it and/or modify it under
 // the terms of the GNU General Public License as published by the
 // Free Software Foundation; either version 2 of the License, or (at
 // your option) any later version.
 //
 // It is distributed in the hope that it will be useful, but WITHOUT
 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 // or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
 // License for more details.
 //
 // You should have received a copy of the GNU General Public License
 // along with this code. If not, see <http://www.gnu.org/licenses/>.
 //----------------------------------------------------------------------
 
 #include <fastjet/JetDefinition.hh>
 #include <fastjet/CompositeJetStructure.hh> // to derive the ReclusterStructure from CompositeJetStructure
 #include <fastjet/tools/Transformer.hh>     // to derive Recluster from Transformer
 #include <iostream>
 #include <string>
 
 FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh
 
 namespace contrib{
 
 //----------------------------------------------------------------------
 /// \class Recluster
 /// Class that helps reclustering a jet with a new jet definition. 
 ///
 /// **This class is DEPRECATED and you are advised to use the
 /// fastjet::Recluster class instead, from "fastjet/tools/Recluster.hh".**
 ///
 /// The result of the reclustering is returned as a single PseudoJet
 /// with a CompositeJet structure. The pieces of that PseudoJet will
 /// be the individual subjets
 ///
 /// When constructed from a JetDefinition, that definition will be
 /// used to obtain the subjets.  When constructed from a JetAlgorithm
 /// and parameters (0 parameters for e+e-, just R or R and an extra
 /// parameter for others) the recombination scheme will be taken as
 /// the same one used to initially cluster the original jet.
 ///
 /// The result of this transformer depends on its usage. There are two
 /// typical use-cases: either we recluster one fat jet into subjets,
 /// OR, we recluster the jet with a different jet alg. When Recluster
 /// is created from a full jet definition. The last parameter of the
 /// constructors below dicatate that behaviour: if "single" is true
 /// (the default), a single jet, issued from a regular clustering is
 /// returned (if there are more than one, the hardest is taken);
 /// otherwise (single==false), the result will be a composite jet with
 /// each subjet as pieces
 /// 
 /// Open points for discussion:
 ///
 ///  - do we add an option to force area support? [could be useful
 ///    e.g. for the filter with a subtractor where area support is
 ///    mandatory]
 ///
 class Recluster : public Transformer {
 public:
   /// define a recluster that decomposes a jet into subjets using a
   /// generic JetDefinition
   ///
   ///  \param subjet_def   the jet definition applied to obtain the subjets
   ///  \param single       when true, cluster the jet in a single jet (the
   ///                      hardest one) with an associated ClusterSequence, 
   ///                      otherwise return a composite jet with subjets
   ///                      as pieces.
   Recluster(const JetDefinition & subjet_def, bool single=true)
     : _subjet_def(subjet_def), _use_full_def(true), _single(single) {}
 
   /// define a recluster that decomposes a jet into subjets using a
   /// JetAlgorithm and its parameters
   ///
   ///  \param subjet_alg    the jet algorithm applied to obtain the subjets
   ///  \param subjet_radius the jet radius if required
   ///  \param subjet_extra  optional extra parameters for the jet algorithm (only when needed)
   ///  \param single        when true, cluster the jet in a single jet (the
   ///                       hardest one) with an associated ClusterSequence, 
   ///                       otherwise return a composite jet with subjets
   ///                       as pieces.
   /// 
   /// Typically, for e+e- algoriothm you should use the third version
   /// below with no parameters, for "standard" pp algorithms, just the
   /// clustering radius has to be specified and for genkt-type of
   /// algorithms, both the radius and the extra parameter have to be
   /// specified.
   Recluster(JetAlgorithm subjet_alg, double subjet_radius, double subjet_extra,
             bool single=true)
     : _subjet_alg(subjet_alg), _use_full_def(false), 
       _subjet_radius(subjet_radius), _has_subjet_radius(true), 
       _subjet_extra(subjet_extra), _has_subjet_extra(true), _single(single) {}
   Recluster(JetAlgorithm subjet_alg, double subjet_radius, bool single=true)
     : _subjet_alg(subjet_alg), _use_full_def(false), 
       _subjet_radius(subjet_radius), _has_subjet_radius(true),
       _has_subjet_extra(false), _single(single) {}
   Recluster(JetAlgorithm subjet_alg, bool single=true)
     : _subjet_alg(subjet_alg), _use_full_def(false), 
       _has_subjet_radius(false), _has_subjet_extra(false), _single(single) {}
 
   /// default dtor
   virtual ~Recluster(){};
 
   //----------------------------------------------------------------------
   // standard Transformer behaviour inherited from the base class
   // (i.e. result(), description() and structural info)
 
   /// runs the reclustering and sets kept and rejected to be the jets of interest
   /// (with non-zero rho, they will have been subtracted).
   ///
   /// \param jet    the jet that gets reclustered
   /// \return the reclustered jet
   virtual PseudoJet result(const PseudoJet & jet) const;
 
   /// class description
   virtual std::string description() const;
 
   // the type of the associated structure
   typedef CompositeJetStructure StructureType;
 
 private:
   /// set the reclustered elements in the simple case of C/A+C/A
   void _recluster_cafilt(const std::vector<PseudoJet> & all_pieces,
                          std::vector<PseudoJet> & subjets,
                          double Rfilt) const;
 
   /// set the reclustered elements in the generic re-clustering case
   void _recluster_generic(const PseudoJet & jet, 
                           std::vector<PseudoJet> & subjets,
                           const JetDefinition & subjet_def,
                           bool do_areas) const;
   
   // a series of checks
   //--------------------------------------------------------------------
   /// get the pieces down to the fundamental pieces
   bool _get_all_pieces(const PseudoJet &jet, std::vector<PseudoJet> &all_pieces) const;
 
   /// get the common recombiner to all pieces (NULL if none)
   const JetDefinition::Recombiner* _get_common_recombiner(const std::vector<PseudoJet> &all_pieces) const;
 
   /// construct the proper jet definition ensuring that the recombiner
   /// is taken from the underlying pieces (an error is thrown if the
   /// pieces do no share a common recombiner)
   void _build_jet_def_with_recombiner(const std::vector<PseudoJet> &all_pieces, 
                                       JetDefinition &subjet_def) const;
 
   /// check if one can apply the simplified trick for C/A subjets
   bool _check_ca(const std::vector<PseudoJet> &all_pieces, 
                  const JetDefinition &subjet_def) const;
 
   /// check if the jet (or all its pieces) have explicit ghosts
   /// (assuming the jet has area support
   ///
   /// Note that if the jet has an associated cluster sequence that is no
   /// longer valid, an error will be thrown
   bool _check_explicit_ghosts(const std::vector<PseudoJet> &all_pieces) const;
 
   JetDefinition _subjet_def;   ///< the jet definition to use to extract the subjets
   JetAlgorithm  _subjet_alg;   ///< the jet algorithm to be used
   bool _use_full_def;          ///< true when the full JetDefinition is supplied to the ctor
   double _subjet_radius;       ///< the jet radius (only if needed for the jet alg)
   bool _has_subjet_radius;     ///< the subjet radius has been specified
   double _subjet_extra;        ///< the jet alg extra param (only if needed)
   bool _has_subjet_extra;      ///< the extra param has been specified
 
   bool _single;                ///< (true) return a single jet with a
                                ///< regular clustering or (false) a
                                ///< composite jet with subjets as pieces
 
   static LimitedWarning   _explicit_ghost_warning;
 };
 
 } // namespace contrib
 
 FASTJET_END_NAMESPACE      // defined in fastjet/internal/base.hh
 
 #endif   // __FASTJET_CONTRIB_TOOLS_RECLUSTER_HH__

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