sampling.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_SAMPLING_H_
#define RTABMAP_FLANN_SAMPLING_H_
 
#include "rtflann/util/matrix.h"
#include "rtflann/util/random.h"
 
namespace rtflann
{
 
template<typename T>
Matrix<T> random_sample(Matrix<T>& srcMatrix, size_t size, bool remove = false)
{
        UniqueRandom rand_unique(srcMatrix.rows);
    Matrix<T> newSet(new T[size * srcMatrix.cols], size,srcMatrix.cols);
 
    T* src,* dest;
    for (size_t i=0; i<size; ++i) {
        size_t r;
        if (remove) {
            r = static_cast<size_t>(rand_int(srcMatrix.rows-i));
        }
        else {
                r = static_cast<size_t>(rand_unique.next());
        }
        dest = newSet[i];
        src = srcMatrix[r];
        std::copy(src, src+srcMatrix.cols, dest);
        if (remove) {
            src = srcMatrix[srcMatrix.rows-i-1];
            dest = srcMatrix[r];
            std::copy(src, src+srcMatrix.cols, dest);
        }
    }
    if (remove) {
        srcMatrix.rows -= size;
    }
    return newSet;
}
 
} // namespace
 
 
#endif /* FLANN_SAMPLING_H_ */