ground_truth.h

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00004  * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
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00030 
00031 #ifndef OPENCV_FLANN_GROUND_TRUTH_H_
00032 #define OPENCV_FLANN_GROUND_TRUTH_H_
00033 
00034 #include "dist.h"
00035 #include "matrix.h"
00036 
00037 
00038 namespace cvflann
00039 {
00040 
00041 template <typename Distance>
00042 void find_nearest(const Matrix<typename Distance::ElementType>& dataset, typename Distance::ElementType* query, int* matches, int nn,
00043                   int skip = 0, Distance distance = Distance())
00044 {
00045     typedef typename Distance::ResultType DistanceType;
00046     int n = nn + skip;
00047 
00048     std::vector<int> match(n);
00049     std::vector<DistanceType> dists(n);
00050 
00051     dists[0] = distance(dataset[0], query, dataset.cols);
00052     match[0] = 0;
00053     int dcnt = 1;
00054 
00055     for (size_t i=1; i<dataset.rows; ++i) {
00056         DistanceType tmp = distance(dataset[i], query, dataset.cols);
00057 
00058         if (dcnt<n) {
00059             match[dcnt] = (int)i;
00060             dists[dcnt++] = tmp;
00061         }
00062         else if (tmp < dists[dcnt-1]) {
00063             dists[dcnt-1] = tmp;
00064             match[dcnt-1] = (int)i;
00065         }
00066 
00067         int j = dcnt-1;
00068         // bubble up
00069         while (j>=1 && dists[j]<dists[j-1]) {
00070             std::swap(dists[j],dists[j-1]);
00071             std::swap(match[j],match[j-1]);
00072             j--;
00073         }
00074     }
00075 
00076     for (int i=0; i<nn; ++i) {
00077         matches[i] = match[i+skip];
00078     }
00079 }
00080 
00081 
00082 template <typename Distance>
00083 void compute_ground_truth(const Matrix<typename Distance::ElementType>& dataset, const Matrix<typename Distance::ElementType>& testset, Matrix<int>& matches,
00084                           int skip=0, Distance d = Distance())
00085 {
00086     for (size_t i=0; i<testset.rows; ++i) {
00087         find_nearest<Distance>(dataset, testset[i], matches[i], (int)matches.cols, skip, d);
00088     }
00089 }
00090 
00091 
00092 }
00093 
00094 #endif //OPENCV_FLANN_GROUND_TRUTH_H_