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4 * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
5 * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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30
31#ifndef OPENCV_FLANN_GROUND_TRUTH_H_
32#define OPENCV_FLANN_GROUND_TRUTH_H_
33
34#include "dist.h"
35#include "matrix.h"
36
37
38namespace cvflann
39{
40
41template <typename Distance>
42void find_nearest(const Matrix<typename Distance::ElementType>& dataset, typename Distance::ElementType* query, int* matches, int nn,
43                  int skip = 0, Distance distance = Distance())
44{
45    typedef typename Distance::ResultType DistanceType;
46    int n = nn + skip;
47
48    std::vector<int> match(n);
49    std::vector<DistanceType> dists(n);
50
51    dists[0] = distance(dataset[0], query, dataset.cols);
52    match[0] = 0;
53    int dcnt = 1;
54
55    for (size_t i=1; i<dataset.rows; ++i) {
56        DistanceType tmp = distance(dataset[i], query, dataset.cols);
57
58        if (dcnt<n) {
59            match[dcnt] = (int)i;
60            dists[dcnt++] = tmp;
61        }
62        else if (tmp < dists[dcnt-1]) {
63            dists[dcnt-1] = tmp;
64            match[dcnt-1] = (int)i;
65        }
66
67        int j = dcnt-1;
68        // bubble up
69        while (j>=1 && dists[j]<dists[j-1]) {
70            std::swap(dists[j],dists[j-1]);
71            std::swap(match[j],match[j-1]);
72            j--;
73        }
74    }
75
76    for (int i=0; i<nn; ++i) {
77        matches[i] = match[i+skip];
78    }
79}
80
81
82template <typename Distance>
83void compute_ground_truth(const Matrix<typename Distance::ElementType>& dataset, const Matrix<typename Distance::ElementType>& testset, Matrix<int>& matches,
84                          int skip=0, Distance d = Distance())
85{
86    for (size_t i=0; i<testset.rows; ++i) {
87        find_nearest<Distance>(dataset, testset[i], matches[i], (int)matches.cols, skip, d);
88    }
89}
90
91
92}
93
94#endif //OPENCV_FLANN_GROUND_TRUTH_H_
95