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ClosestPair2DBase.hh
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28 
29 #ifndef __FASTJET_CLOSESTPAIR2DBASE__HH__
30 #define __FASTJET_CLOSESTPAIR2DBASE__HH__
31 
32 #include<vector>
33 #include "fastjet/internal/base.hh"
34 
35 FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh
36 
37 //----------------------------------------------------------------------
38 /// \if internal_doc
39 /// @ingroup internal
40 /// \class Coord2D
41 /// class for representing 2d coordinates and carrying out some basic
42 /// operations on them
43 /// \endif
44 class Coord2D {
45 public:
46  double x, y;
47 
48  Coord2D() {};
49 
50  Coord2D(double a, double b): x(a), y(b) {};
51 
52  /// return the vector difference between two coordinates
53  Coord2D operator-(const Coord2D & other) const {
54  return Coord2D(x - other.x, y - other.y);};
55 
56  /// return the vector sum between two coordinates
57  Coord2D operator+(const Coord2D & other) const {
58  return Coord2D(x + other.x, y + other.y);};
59 
60  /// return the product of the coordinate with the factor
61  Coord2D operator*(double factor) const {return Coord2D(factor*x,factor*y);};
62  friend Coord2D operator*(double factor, const Coord2D & coord) {
63  return Coord2D(factor*coord.x,factor*coord.y);
64  }
65 
66  /// division of each component of coordinate
67  Coord2D operator/(double divisor) const {
68  return Coord2D(x / divisor, y / divisor);};
69 
70  /// return the squared distance between two coordinates
71  friend double distance2(const Coord2D & a, const Coord2D & b) {
72  double dx = a.x - b.x, dy = a.y-b.y;
73  return dx*dx+dy*dy;
74  };
75  /// return the squared distance between two coordinates
76  double distance2(const Coord2D & b) const {
77  double dx = x - b.x, dy = y-b.y;
78  return dx*dx+dy*dy;
79  };
80 };
81 
82 
83 //----------------------------------------------------------------------
84 /// \if internal_doc
85 /// @ingroup internal
86 /// \class ClosestPair2DBase
87 /// abstract base class for finding closest pairs in 2D
88 /// \endif
89 class ClosestPair2DBase {
90 public:
91  /// provides the IDs of the closest pair as well as the squared
92  /// distance between them
93  virtual void closest_pair(unsigned int & ID1, unsigned int & ID2,
94  double & distance2) const = 0;
95 
96  /// removes the entry labelled by ID from the object;
97  virtual void remove(unsigned int ID) = 0;
98 
99  /// inserts the position into the closest pair structure and returns the
100  /// ID that has been allocated for the object.
101  virtual unsigned int insert(const Coord2D & position) = 0;
102 
103  /// replaces the specified ID1 and ID2 with something at a new position
104  /// assuming that ID1 and ID2 are in sequence wrt position; it returns
105  /// the ID of the new object...
106  virtual unsigned int replace(unsigned int ID1, unsigned int ID2,
107  const Coord2D & position) {
108  remove(ID1);
109  remove(ID2);
110  unsigned new_ID = insert(position);
111  return(new_ID);
112  };
113 
114  /// replaces IDs_to_remove with points at the new_positions
115  /// indicating the IDs allocated to the new points in new_IDs
116  virtual void replace_many(const std::vector<unsigned int> & IDs_to_remove,
117  const std::vector<Coord2D> & new_positions,
118  std::vector<unsigned int> & new_IDs) {
119  for(unsigned i = 0; i < IDs_to_remove.size(); i++) {
120  remove(IDs_to_remove[i]);}
121  new_IDs.resize(0);
122  for(unsigned i = 0; i < new_positions.size(); i++) {
123  new_IDs.push_back(insert(new_positions[i]));}
124  }
125 
126  virtual unsigned int size() = 0;
127 
128  virtual ~ClosestPair2DBase() {};
129 
130 };
131 
132 
133 FASTJET_END_NAMESPACE
134 
135 #endif // __FASTJET_CLOSESTPAIR2DBASE__HH__