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NearestNeighborsSqrtApprox.h
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34 
35 /* Author: Ioan Sucan */
36 
37 #ifndef OMPL_DATASTRUCTURES_NEAREST_NEIGHBORS_SQRT_APPROX_
38 #define OMPL_DATASTRUCTURES_NEAREST_NEIGHBORS_SQRT_APPROX_
39 
40 #include "ompl/datastructures/NearestNeighborsLinear.h"
41 #include <algorithm>
42 #include <cmath>
43 
44 namespace ompl
45 {
56  template<typename _T>
58  {
59  public:
61  {
62  }
63 
64  virtual ~NearestNeighborsSqrtApprox(void)
65  {
66  }
67 
68  virtual void clear(void)
69  {
71  checks_ = 0;
72  offset_ = 0;
73  }
74 
75  virtual void add(const _T &data)
76  {
79  }
80 
81  virtual void add(const std::vector<_T> &data)
82  {
85  }
86 
87  virtual bool remove(const _T &data)
88  {
89  bool result = NearestNeighborsLinear<_T>::remove(data);
90  if (result)
92  return result;
93  }
94 
95  virtual _T nearest(const _T &data) const
96  {
97  const std::size_t n = NearestNeighborsLinear<_T>::data_.size();
98  std::size_t pos = n;
99 
100  if (checks_ > 0 && n > 0)
101  {
102  double dmin = 0.0;
103  for (std::size_t j = 0 ; j < checks_ ; ++j)
104  {
105  std::size_t i = (j * checks_ + offset_) % n;
106 
108  if (pos == n || dmin > distance)
109  {
110  pos = i;
111  dmin = distance;
112  }
113  }
114  offset_ = (offset_ + 1) % checks_;
115  }
116  if (pos != n)
118 
119  throw Exception("No elements found in nearest neighbors data structure");
120  }
121 
122  protected:
123 
125  inline void updateCheckCount(void)
126  {
127  checks_ = 1 + (std::size_t)floor(sqrt((double)NearestNeighborsLinear<_T>::data_.size()));
128  }
129 
131  std::size_t checks_;
132 
134  mutable std::size_t offset_;
135 
136  };
137 
138 }
139 
140 #endif