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random_sample.hpp
/*
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* $Id: extract_indices.hpp 1897 2011-07-26 20:35:49Z rusu $
*
*/
#ifndef PCL_FILTERS_IMPL_RANDOM_SAMPLE_H_
#define PCL_FILTERS_IMPL_RANDOM_SAMPLE_H_
#include <pcl/filters/random_sample.h>
///////////////////////////////////////////////////////////////////////////////
template<typename PointT>
void
pcl::RandomSample<PointT>::applyFilter (Indices &indices)
{
std::size_t N = indices_->size ();
std::size_t sample_size = negative_ ? N - sample_ : sample_;
// If sample size is 0 or if the sample size is greater then input cloud size
// then return all indices
if (sample_size >= N)
{
indices = *indices_;
removed_indices_->clear ();
}
else
{
// Resize output indices to sample size
indices.resize (sample_size);
if (extract_removed_indices_)
removed_indices_->resize (N - sample_size);
// Set random seed so derived indices are the same each time the filter runs
std::srand (seed_);
// Algorithm S
std::size_t i = 0;
std::size_t index = 0;
std::vector<bool> added;
if (extract_removed_indices_)
added.resize (indices_->size (), false);
std::size_t n = sample_size;
while (n > 0)
{
// Step 1: [Generate U.] Generate a random variate U that is uniformly distributed between 0 and 1.
const float U = unifRand ();
// Step 2: [Test.] If N * U > n, go to Step 4.
if ((N * U) <= n)
{
// Step 3: [Select.] Select the next record in the file for the sample, and set n : = n - 1.
if (extract_removed_indices_)
added[index] = true;
indices[i++] = (*indices_)[index];
--n;
}
// Step 4: [Don't select.] Skip over the next record (do not include it in the sample).
// Set N : = N - 1.
--N;
++index;
// If n > 0, then return to Step 1; otherwise, the sample is complete and the algorithm terminates.
}
// Now populate removed_indices_ appropriately
if (extract_removed_indices_)
{
std::size_t ri = 0;
for (std::size_t i = 0; i < added.size (); i++)
{
if (!added[i])
{
(*removed_indices_)[ri++] = (*indices_)[i];
}
}
}
}
}
#define PCL_INSTANTIATE_RandomSample(T) template class PCL_EXPORTS pcl::RandomSample<T>;
#endif // PCL_FILTERS_IMPL_RANDOM_SAMPLE_H_
pcl::RandomSample::applyFilter
void applyFilter(Indices &indices) override
Sample of point indices.
Definition random_sample.hpp:47
pcl::Indices
IndicesAllocator<> Indices
Type used for indices in PCL.
Definition types.h:133