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ompl::NearestNeighborsGNAT< _T > Class Template Reference

Geometric Near-neighbor Access Tree (GNAT), a data structure for nearest neighbor search. More...

`#include <ompl/datastructures/NearestNeighborsGNAT.h>`

Inheritance diagram for ompl::NearestNeighborsGNAT< _T >:

## Classes | |

class | Node |

The class used internally to define the GNAT. More... | |

## Public Member Functions | |

NearestNeighborsGNAT (unsigned int degree=8, unsigned int minDegree=4, unsigned int maxDegree=12, unsigned int maxNumPtsPerLeaf=50, unsigned int removedCacheSize=500, bool rebalancing=false) | |

void | setDistanceFunction (const typename NearestNeighbors< _T >::DistanceFunction &distFun) override |

Set the distance function to use. | |

void | clear () override |

Clear the datastructure. | |

bool | reportsSortedResults () const override |

Return true if the solutions reported by this data structure are sorted, when calling nearestK / nearestR. | |

void | add (const _T &data) override |

Add an element to the datastructure. | |

void | add (const std::vector< _T > &data) override |

Add a vector of points. | |

void | rebuildDataStructure () |

Rebuild the internal data structure. | |

bool | remove (const _T &data) override |

Remove data from the tree. The element won't actually be removed immediately, but just marked for removal in the removed_ cache. When the cache is full, the tree will be rebuilt and the elements marked for removal will actually be removed. | |

_T | nearest (const _T &data) const override |

Get the nearest neighbor of a point. | |

void | nearestK (const _T &data, std::size_t k, std::vector< _T > &nbh) const override |

Return the k nearest neighbors in sorted order. | |

void | nearestR (const _T &data, double radius, std::vector< _T > &nbh) const override |

Return the nearest neighbors within distance `radius` in sorted order. | |

std::size_t | size () const override |

Get the number of elements in the datastructure. | |

void | list (std::vector< _T > &data) const override |

Get all the elements in the datastructure. | |

void | integrityCheck () |

Public Member Functions inherited from ompl::NearestNeighbors< _T > | |

virtual void | setDistanceFunction (const DistanceFunction &distFun) |

Set the distance function to use. | |

const DistanceFunction & | getDistanceFunction () const |

Get the distance function used. | |

## Protected Types | |

using | GNAT = NearestNeighborsGNAT< _T > |

## Protected Member Functions | |

bool | isRemoved (const _T &data) const |

Return true iff data has been marked for removal. | |

bool | nearestKInternal (const _T &data, std::size_t k, NearQueue &nbhQueue) const |

Return in nbhQueue the k nearest neighbors of data. For k=1, return true if the nearest neighbor is a pivot. (which is important during removal; removing pivots is a special case). | |

void | nearestRInternal (const _T &data, double radius, NearQueue &nbhQueue) const |

Return in nbhQueue the elements that are within distance radius of data. | |

void | postprocessNearest (NearQueue &nbhQueue, std::vector< _T > &nbh) const |

Convert the internal data structure used for storing neighbors to the vector that NearestNeighbor API requires. | |

## Protected Attributes | |

Node * | tree_ {nullptr} |

The data structure containing the elements stored in this structure. | |

unsigned int | degree_ |

The desired degree of each node. | |

unsigned int | minDegree_ |

After splitting a Node, each child Node has degree equal to the default degree times the fraction of data elements from the original node that got assigned to that child Node. However, its degree can be no less than minDegree_. | |

unsigned int | maxDegree_ |

After splitting a Node, each child Node has degree equal to the default degree times the fraction of data elements from the original node that got assigned to that child Node. However, its degree can be no larger than maxDegree_. | |

unsigned int | maxNumPtsPerLeaf_ |

Maximum number of elements allowed to be stored in a Node before it needs to be split into several nodes. | |

std::size_t | size_ {0} |

Number of elements stored in the tree. | |

std::size_t | rebuildSize_ |

If size_ exceeds rebuildSize_, the tree will be rebuilt (and automatically rebalanced), and rebuildSize_ will be doubled. | |

std::size_t | removedCacheSize_ |

Maximum number of removed elements that can be stored in the removed_ cache. If the cache is full, the tree will be rebuilt with the elements in removed_ actually removed from the tree. | |

GreedyKCenters< _T > | pivotSelector_ |

The data structure used to split data into subtrees. | |

std::unordered_set< const _T * > | removed_ |

Cache of removed elements. | |

Protected Attributes inherited from ompl::NearestNeighbors< _T > | |

DistanceFunction | distFun_ |

The used distance function. | |

## Friends | |

std::ostream & | operator<< (std::ostream &out, const NearestNeighborsGNAT< _T > &gnat) |

Print a GNAT structure (mostly useful for debugging purposes). | |

## Additional Inherited Members | |

Public Types inherited from ompl::NearestNeighbors< _T > | |

using | DistanceFunction = std::function< double(const _T &, const _T &)> |

The definition of a distance function. | |

## Detailed Description

### template<typename _T>

class ompl::NearestNeighborsGNAT< _T >

Geometric Near-neighbor Access Tree (GNAT), a data structure for nearest neighbor search.

If GNAT_SAMPLER is defined, then extra code will be enabled to sample elements from the GNAT with probability inversely proportial to their local density.

- External documentation
- S. Brin, Near neighbor search in large metric spaces, in
*Proc. 21st Conf. on Very Large Databases (VLDB)*, pp. 574–584, 1995.

B. Gipson, M. Moll, and L.E. Kavraki, Resolution independent density estimation for motion planning in high-dimensional spaces, in *IEEE Intl. Conf. on Robotics and Automation*, 2013. [PDF]

Definition at line 72 of file NearestNeighborsGNAT.h.

The documentation for this class was generated from the following file:

- ompl/datastructures/NearestNeighborsGNAT.h