text: /***********************************************************************
   * Software License Agreement (BSD License)
   *
   * 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.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
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   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
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   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *************************************************************************/
  
  #ifndef OPENCV_FLANN_SAMPLING_H_
  #define OPENCV_FLANN_SAMPLING_H_
  
  #include "matrix.h"
  #include "random.h"
  
  namespace cvflann
  {
  
  template<typename T>
  Matrix<T> random_sample(Matrix<T>& srcMatrix, long size, bool remove = false)
  {
      Matrix<T> newSet(new T[size * srcMatrix.cols], size,srcMatrix.cols);
  
      T* src,* dest;
      for (long i=0; i<size; ++i) {
          long r = rand_int((int)(srcMatrix.rows-i));
          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;
  }
  
  template<typename T>
  Matrix<T> random_sample(const Matrix<T>& srcMatrix, size_t size)
  {
      UniqueRandom rand((int)srcMatrix.rows);
      Matrix<T> newSet(new T[size * srcMatrix.cols], size,srcMatrix.cols);
  
      T* src,* dest;
      for (size_t i=0; i<size; ++i) {
          long r = rand.next();
          dest = newSet[i];
          src = srcMatrix[r];
          std::copy(src, src+srcMatrix.cols, dest);
      }
      return newSet;
  }
  
  } // namespace
  
  #endif /* OPENCV_FLANN_SAMPLING_H_ */
  