std::vector<std::pair<population::size_type,std::vector<population::individual_type>::size_type> >
random_r_policy::select(const std::vector<population::individual_type> &immigrants, const population &dest) const
{
const population::size_type rate_limit = std::min<population::size_type>(get_n_individuals(dest),boost::numeric_cast<population::size_type>(immigrants.size()));
// Temporary vectors to store sorted indices of the populations.
std::vector<population::size_type> immigrants_idx(boost::numeric_cast<std::vector<population::size_type>::size_type>(immigrants.size()));
std::vector<population::size_type> dest_idx(boost::numeric_cast<std::vector<population::size_type>::size_type>(dest.size()));
// Fill in the arrays of indices.
iota(immigrants_idx.begin(),immigrants_idx.end(),population::size_type(0));
iota(dest_idx.begin(),dest_idx.end(),population::size_type(0));
// Permute the indices (immigrants).
for (population::size_type i = 0; i < rate_limit; ++i) {
population::size_type next_idx = i + (m_urng() % (rate_limit - i));
if (next_idx != i) {
std::swap(immigrants_idx[i], immigrants_idx[next_idx]);
}
}
// Permute the indices (destination).
for (population::size_type i = 0; i < rate_limit; ++i) {
population::size_type next_idx = i + (m_urng() % (dest.size() - i));
if (next_idx != i) {
std::swap(dest_idx[i], dest_idx[next_idx]);
}
}
// Return value.
std::vector<std::pair<population::size_type,std::vector<population::individual_type>::size_type> >
retval;
for (population::size_type i = 0; i < rate_limit; ++i) {
retval.push_back(std::make_pair(dest_idx[i],immigrants_idx[i]));
}
return retval;
}
// Selection implementation.
std::vector<std::pair<population::size_type,std::vector<population::individual_type>::size_type> >
worst_r_policy::select(const std::vector<population::individual_type> &immigrants, const population &dest) const
{
const population::size_type rate_limit = std::min<population::size_type>(get_n_individuals(dest),boost::numeric_cast<population::size_type>(immigrants.size()));
// Temporary vectors to store sorted indices of the populations.
std::vector<population::size_type> immigrants_idx(boost::numeric_cast<std::vector<population::size_type>::size_type>(immigrants.size()));
std::vector<population::size_type> dest_idx(boost::numeric_cast<std::vector<population::size_type>::size_type>(dest.size()));
// Fill in the arrays of indices.
iota(immigrants_idx.begin(),immigrants_idx.end(),population::size_type(0));
iota(dest_idx.begin(),dest_idx.end(),population::size_type(0));
// Sort the arrays of indices.
// From best to worst.
std::sort(immigrants_idx.begin(),immigrants_idx.end(),indirect_individual_sorter<std::vector<population::individual_type> >(immigrants,dest));
// From worst to best.
std::sort(dest_idx.begin(),dest_idx.end(),indirect_individual_sorter<population>(dest,dest));
std::reverse(dest_idx.begin(),dest_idx.end());
// Create the result.
std::vector<std::pair<population::size_type,std::vector<population::individual_type>::size_type> > result;
for (population::size_type i = 0; i < rate_limit; ++i) {
// Similar to fair policy, but replace unconditionally, without checking if the incoming individuals are better.
result.push_back(std::make_pair(dest_idx[i],immigrants_idx[i]));
}
return result;
}
