result_set.h

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 *
 * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
 * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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#ifndef RTABMAP_FLANN_RESULTSET_H
#define RTABMAP_FLANN_RESULTSET_H

#include <algorithm>
#include <cstring>
#include <iostream>
#include <limits>
#include <set>
#include <vector>

namespace rtflann
{

/* This record represents a branch point when finding neighbors in
    the tree.  It contains a record of the minimum distance to the query
    point, as well as the node at which the search resumes.
 */

template <typename T, typename DistanceType>
struct BranchStruct
{
    T node;           /* Tree node at which search resumes */
    DistanceType mindist;     /* Minimum distance to query for all nodes below. */

    BranchStruct() {}
    BranchStruct(const T& aNode, DistanceType dist) : node(aNode), mindist(dist) {}

    bool operator<(const BranchStruct<T, DistanceType>& rhs) const
    {
        return mindist<rhs.mindist;
    }
};


template <typename DistanceType>
struct DistanceIndex
{
    DistanceIndex(DistanceType dist, size_t index) :
        dist_(dist), index_(index)
    {
    }
    bool operator<(const DistanceIndex& dist_index) const
    {
        return (dist_ < dist_index.dist_) || ((dist_ == dist_index.dist_) && index_ < dist_index.index_);
    }
    DistanceType dist_;
    size_t index_;
};


template <typename DistanceType>
class ResultSet
{
public:
    virtual ~ResultSet() {}

    virtual bool full() const = 0;

    virtual void addPoint(DistanceType dist, size_t index) = 0;

    virtual DistanceType worstDist() const = 0;

};

template <typename DistanceType>
class KNNSimpleResultSet : public ResultSet<DistanceType>
{
public:
        typedef DistanceIndex<DistanceType> DistIndex;

        KNNSimpleResultSet(size_t capacity_) :
        capacity_(capacity_)
    {
                // reserving capacity to prevent memory re-allocations
                dist_index_.resize(capacity_, DistIndex(std::numeric_limits<DistanceType>::max(),-1));
        clear();
    }

    ~KNNSimpleResultSet()
    {
    }

    void clear()
    {
        worst_distance_ = std::numeric_limits<DistanceType>::max();
        dist_index_[capacity_-1].dist_ = worst_distance_;
        count_ = 0;
    }

    size_t size() const
    {
        return count_;
    }

    bool full() const
    {
        return count_==capacity_;
    }

    void addPoint(DistanceType dist, size_t index)
    {
        if (dist>=worst_distance_) return;

        if (count_ < capacity_) ++count_;
        size_t i;
        for (i=count_-1; i>0; --i) {
#ifdef FLANN_FIRST_MATCH
            if ( (dist_index_[i-1].dist_>dist) || ((dist==dist_index_[i-1].dist_)&&(dist_index_[i-1].index_>index)) )
#else
            if (dist_index_[i-1].dist_>dist)
#endif
            {
                dist_index_[i] = dist_index_[i-1];
            }
            else break;
        }
        dist_index_[i].dist_ = dist;
        dist_index_[i].index_ = index;
        worst_distance_ = dist_index_[capacity_-1].dist_;
    }

    void copy(size_t* indices, DistanceType* dists, size_t num_elements, bool sorted = true)
    {
        size_t n = std::min(count_, num_elements);
        for (size_t i=0; i<n; ++i) {
                *indices++ = dist_index_[i].index_;
                *dists++ = dist_index_[i].dist_;
        }
    }

    DistanceType worstDist() const
    {
        return worst_distance_;
    }

private:
    size_t capacity_;
    size_t count_;
    DistanceType worst_distance_;
    std::vector<DistIndex> dist_index_;
};

template <typename DistanceType>
class KNNResultSet : public ResultSet<DistanceType>
{
public:
        typedef DistanceIndex<DistanceType> DistIndex;

    KNNResultSet(int capacity) : capacity_(capacity)
    {
                // reserving capacity to prevent memory re-allocations
                dist_index_.resize(capacity_, DistIndex(std::numeric_limits<DistanceType>::max(),-1));
        clear();
    }

    ~KNNResultSet()
    {

    }

    void clear()
    {
        worst_distance_ = std::numeric_limits<DistanceType>::max();
        dist_index_[capacity_-1].dist_ = worst_distance_;
        count_ = 0;
    }

    size_t size() const
    {
        return count_;
    }

    bool full() const
    {
        return count_ == capacity_;
    }


    void addPoint(DistanceType dist, size_t index)
    {
        if (dist >= worst_distance_) return;
        size_t i;
        for (i = count_; i > 0; --i) {
#ifdef FLANN_FIRST_MATCH
            if ( (dist_index_[i-1].dist_<=dist) && ((dist!=dist_index_[i-1].dist_)||(dist_index_[i-1].index_<=index)) )
#else
            if (dist_index_[i-1].dist_<=dist)
#endif
            {
                // Check for duplicate indices
                for (size_t j = i - 1; dist_index_[j].dist_ == dist && j--;) {
                    if (dist_index_[j].index_ == index) {
                        return;
                    }
                }
                break;
            }
        }
        if (count_ < capacity_) ++count_;
        for (size_t j = count_-1; j > i; --j) {
            dist_index_[j] = dist_index_[j-1];
        }
        dist_index_[i].dist_ = dist;
        dist_index_[i].index_ = index;
        worst_distance_ = dist_index_[capacity_-1].dist_;
    }

    void copy(size_t* indices, DistanceType* dists, size_t num_elements, bool sorted = true)
    {
        size_t n = std::min(count_, num_elements);
        for (size_t i=0; i<n; ++i) {
                *indices++ = dist_index_[i].index_;
                *dists++ = dist_index_[i].dist_;
        }
    }

    DistanceType worstDist() const
    {
        return worst_distance_;
    }

private:
    size_t capacity_;
    size_t count_;
    DistanceType worst_distance_;
    std::vector<DistIndex> dist_index_;

};



template <typename DistanceType>
class KNNResultSet2 : public ResultSet<DistanceType>
{
public:
        typedef DistanceIndex<DistanceType> DistIndex;

        KNNResultSet2(size_t capacity_) :
        capacity_(capacity_)
    {
                // reserving capacity to prevent memory re-allocations
                dist_index_.reserve(capacity_);
        clear();
    }

    ~KNNResultSet2()
    {
    }

    void clear()
    {
        dist_index_.clear();
        worst_dist_ = std::numeric_limits<DistanceType>::max();
        is_full_ = false;
    }

    size_t size() const
    {
        return dist_index_.size();
    }

    bool full() const
    {
        return is_full_;
    }

    void addPoint(DistanceType dist, size_t index)
    {
        if (dist>=worst_dist_) return;

        if (dist_index_.size()==capacity_) {
                // if result set if filled to capacity, remove farthest element
                std::pop_heap(dist_index_.begin(), dist_index_.end());
                dist_index_.pop_back();
        }

        // add new element
        dist_index_.push_back(DistIndex(dist,index));
        if (is_full_) { // when is_full_==true, we have a heap
                std::push_heap(dist_index_.begin(), dist_index_.end());
        }

        if (dist_index_.size()==capacity_) {
                if (!is_full_) {
                        std::make_heap(dist_index_.begin(), dist_index_.end());
                is_full_ = true;
                }
                // we replaced the farthest element, update worst distance
                worst_dist_ = dist_index_[0].dist_;
        }
    }

    void copy(size_t* indices, DistanceType* dists, size_t num_elements, bool sorted = true)
    {
        if (sorted) {
                // std::sort_heap(dist_index_.begin(), dist_index_.end());
                // sort seems faster here, even though dist_index_ is a heap
                std::sort(dist_index_.begin(), dist_index_.end());
        }
        else {
                if (num_elements<size()) {
                        std::nth_element(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());
                }
        }

        size_t n = std::min(dist_index_.size(), num_elements);
        for (size_t i=0; i<n; ++i) {
                *indices++ = dist_index_[i].index_;
                *dists++ = dist_index_[i].dist_;
        }
    }

    DistanceType worstDist() const
    {
        return worst_dist_;
    }

private:
    size_t capacity_;
    DistanceType worst_dist_;
    std::vector<DistIndex> dist_index_;
    bool is_full_;
};


template <typename DistanceType>
class RadiusResultSet : public ResultSet<DistanceType>
{
public:
        typedef DistanceIndex<DistanceType> DistIndex;

        RadiusResultSet(DistanceType radius_) :
        radius_(radius_)
    {
                // reserving some memory to limit number of re-allocations
                dist_index_.reserve(1024);
        clear();
    }

    ~RadiusResultSet()
    {
    }

    void clear()
    {
        dist_index_.clear();
    }

    size_t size() const
    {
        return dist_index_.size();
    }

    bool full() const
    {
        return true;
    }

    void addPoint(DistanceType dist, size_t index)
    {
        if (dist<radius_) {
                // add new element
                dist_index_.push_back(DistIndex(dist,index));
        }
    }

    void copy(size_t* indices, DistanceType* dists, size_t num_elements, bool sorted = true)
    {
        if (sorted) {
                // std::sort_heap(dist_index_.begin(), dist_index_.end());
                // sort seems faster here, even though dist_index_ is a heap
                std::sort(dist_index_.begin(), dist_index_.end());
        }
        else {
                if (num_elements<size()) {
                        std::nth_element(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());
                }
        }

        size_t n = std::min(dist_index_.size(), num_elements);
        for (size_t i=0; i<n; ++i) {
                *indices++ = dist_index_[i].index_;
                *dists++ = dist_index_[i].dist_;
        }
    }

    DistanceType worstDist() const
    {
        return radius_;
    }

private:
    DistanceType radius_;
    std::vector<DistIndex> dist_index_;
};



template <typename DistanceType>
class KNNRadiusResultSet : public ResultSet<DistanceType>
{
public:
        typedef DistanceIndex<DistanceType> DistIndex;

        KNNRadiusResultSet(DistanceType radius_, size_t capacity_) :
        radius_(radius_), capacity_(capacity_)
    {
                // reserving capacity to prevent memory re-allocations
                dist_index_.reserve(capacity_);
        clear();
    }

    ~KNNRadiusResultSet()
    {
    }

    void clear()
    {
        dist_index_.clear();
        worst_dist_ = radius_;
        is_heap_ = false;
    }

    size_t size() const
    {
        return dist_index_.size();
    }

    bool full() const
    {
        return true;
    }

    void addPoint(DistanceType dist, size_t index)
    {
        if (dist>=worst_dist_) return;

        if (dist_index_.size()==capacity_) {
                // if result set is filled to capacity, remove farthest element
                std::pop_heap(dist_index_.begin(), dist_index_.end());
                dist_index_.pop_back();
        }

        // add new element
        dist_index_.push_back(DistIndex(dist,index));
        if (is_heap_) {
                std::push_heap(dist_index_.begin(), dist_index_.end());
        }

        if (dist_index_.size()==capacity_) {
                // when got to full capacity, make it a heap
                if (!is_heap_) {
                        std::make_heap(dist_index_.begin(), dist_index_.end());
                        is_heap_ = true;
                }
                // we replaced the farthest element, update worst distance
                worst_dist_ = dist_index_[0].dist_;
        }
    }

    void copy(size_t* indices, DistanceType* dists, size_t num_elements, bool sorted = true)
    {
        if (sorted) {
                // std::sort_heap(dist_index_.begin(), dist_index_.end());
                // sort seems faster here, even though dist_index_ is a heap
                std::sort(dist_index_.begin(), dist_index_.end());
        }
        else {
                if (num_elements<size()) {
                        std::nth_element(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());
                }
        }

        size_t n = std::min(dist_index_.size(), num_elements);
        for (size_t i=0; i<n; ++i) {
                *indices++ = dist_index_[i].index_;
                *dists++ = dist_index_[i].dist_;
        }
    }

    DistanceType worstDist() const
    {
        return worst_dist_;
    }

private:
    bool is_heap_;
    DistanceType radius_;
    size_t capacity_;
    DistanceType worst_dist_;
    std::vector<DistIndex> dist_index_;
};



template <typename DistanceType>
class CountRadiusResultSet : public ResultSet<DistanceType>
{
    DistanceType radius;
    size_t count;

public:
    CountRadiusResultSet(DistanceType radius_ ) :
        radius(radius_)
    {
        clear();
    }

    ~CountRadiusResultSet()
    {
    }

    void clear()
    {
        count = 0;
    }

    size_t size() const
    {
        return count;
    }

    bool full() const
    {
        return true;
    }

    void addPoint(DistanceType dist, size_t index)
    {
        if (dist<radius) {
            count++;
        }
    }

    DistanceType worstDist() const
    {
        return radius;
    }

};




template<typename DistanceType>
class UniqueResultSet : public ResultSet<DistanceType>
{
public:
    struct DistIndex
    {
        DistIndex(DistanceType dist, unsigned int index) :
            dist_(dist), index_(index)
        {
        }
        bool operator<(const DistIndex dist_index) const
        {
            return (dist_ < dist_index.dist_) || ((dist_ == dist_index.dist_) && index_ < dist_index.index_);
        }
        DistanceType dist_;
        unsigned int index_;
    };

    UniqueResultSet() :
        worst_distance_(std::numeric_limits<DistanceType>::max())
    {
    }

    inline bool full() const
    {
        return is_full_;
    }

    void copy(size_t* indices, DistanceType* dist, int n_neighbors, bool sorted = true)
    {
        if (n_neighbors<0) n_neighbors = dist_indices_.size();
        int i = 0;
        typedef typename std::set<DistIndex>::const_iterator Iterator;
        for (Iterator dist_index = dist_indices_.begin(), dist_index_end =
                        dist_indices_.end(); (dist_index != dist_index_end) && (i < n_neighbors); ++dist_index, ++indices, ++dist, ++i) {
                *indices = dist_index->index_;
                *dist = dist_index->dist_;
        }
    }

    size_t size() const
    {
        return dist_indices_.size();
    }

    inline DistanceType worstDist() const
    {
        return worst_distance_;
    }
protected:
    bool is_full_;

    DistanceType worst_distance_;

    std::set<DistIndex> dist_indices_;
};


template<typename DistanceType>
class KNNUniqueResultSet : public UniqueResultSet<DistanceType>
{
public:
    KNNUniqueResultSet(unsigned int capacity) : capacity_(capacity)
    {
        this->is_full_ = false;
        this->clear();
    }

    inline void addPoint(DistanceType dist, size_t index)
    {
        // Don't do anything if we are worse than the worst
        if (dist >= worst_distance_) return;
        dist_indices_.insert(DistIndex(dist, index));

        if (is_full_) {
            if (dist_indices_.size() > capacity_) {
                dist_indices_.erase(*dist_indices_.rbegin());
                worst_distance_ = dist_indices_.rbegin()->dist_;
            }
        }
        else if (dist_indices_.size() == capacity_) {
            is_full_ = true;
            worst_distance_ = dist_indices_.rbegin()->dist_;
        }
    }

    void clear()
    {
        dist_indices_.clear();
        worst_distance_ = std::numeric_limits<DistanceType>::max();
        is_full_ = false;
    }

protected:
    typedef typename UniqueResultSet<DistanceType>::DistIndex DistIndex;
    using UniqueResultSet<DistanceType>::is_full_;
    using UniqueResultSet<DistanceType>::worst_distance_;
    using UniqueResultSet<DistanceType>::dist_indices_;

    unsigned int capacity_;
};


template<typename DistanceType>
class RadiusUniqueResultSet : public UniqueResultSet<DistanceType>
{
public:
    RadiusUniqueResultSet(DistanceType radius) :
        radius_(radius)
    {
        is_full_ = true;
    }

    void addPoint(DistanceType dist, size_t index)
    {
        if (dist < radius_) dist_indices_.insert(DistIndex(dist, index));
    }

    inline void clear()
    {
        dist_indices_.clear();
    }


    inline bool full() const
    {
        return true;
    }

    inline DistanceType worstDist() const
    {
        return radius_;
    }
private:
    typedef typename UniqueResultSet<DistanceType>::DistIndex DistIndex;
    using UniqueResultSet<DistanceType>::dist_indices_;
    using UniqueResultSet<DistanceType>::is_full_;

    DistanceType radius_;
};


template<typename DistanceType>
class KNNRadiusUniqueResultSet : public KNNUniqueResultSet<DistanceType>
{
public:
    KNNRadiusUniqueResultSet(DistanceType radius, size_t capacity) : KNNUniqueResultSet<DistanceType>(capacity)
    {
        this->radius_ = radius;
        this->clear();
    }

    void clear()
    {
        dist_indices_.clear();
        worst_distance_ = radius_;
        is_full_ = true;
    }
private:
    using KNNUniqueResultSet<DistanceType>::dist_indices_;
    using KNNUniqueResultSet<DistanceType>::is_full_;
    using KNNUniqueResultSet<DistanceType>::worst_distance_;

    DistanceType radius_;
};
}

#endif //FLANN_RESULTSET_H