subsets.cc

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#include "chi_utils.h"
 
#include <cmath>
 
#define scdouble static_cast<double>
 
namespace chi
{
 
std::vector<SubSetInfo> MakeSubSets(size_t num_items,
                                    size_t desired_num_subsets)
{
  std::vector<SubSetInfo> ss_infos;
  const std::size_t div =
    std::floor(scdouble(num_items) / scdouble(desired_num_subsets));
  const std::size_t rem = num_items % desired_num_subsets;
 
  for (size_t i = 0; i < desired_num_subsets; ++i)
    ss_infos.push_back({0, 0, div});
  for (size_t j = 0; j < rem; ++j)
    ss_infos[j].ss_size += 1;
 
  size_t check_sum = 0;
  for (size_t i = 0; i < desired_num_subsets; ++i)
  {
    ss_infos[i].ss_begin = check_sum;
    check_sum += ss_infos[i].ss_size;
    ss_infos[i].ss_end = check_sum - 1;
  }
 
  return ss_infos;
}
 
} // namespace chi