string kll_sketch::to_string()

in kll/include/kll_sketch_impl.hpp [904:953]

• 46 lines of code
• 11 McCabe index (conditional complexity)

string<A> kll_sketch<T, C, A>::to_string(bool print_levels, bool print_items) const {
  // Using a temporary stream for implementation here does not comply with AllocatorAwareContainer requirements.
  // The stream does not support passing an allocator instance, and alternatives are complicated.
  std::ostringstream os;
  os << "### KLL sketch summary:" << std::endl;
  os << "   K              : " << k_ << std::endl;
  os << "   min K          : " << min_k_ << std::endl;
  os << "   M              : " << (unsigned int) m_ << std::endl;
  os << "   N              : " << n_ << std::endl;
  os << "   Epsilon        : " << std::setprecision(3) << get_normalized_rank_error(false) * 100 << "%" << std::endl;
  os << "   Epsilon PMF    : " << get_normalized_rank_error(true) * 100 << "%" << std::endl;
  os << "   Empty          : " << (is_empty() ? "true" : "false") << std::endl;
  os << "   Estimation mode: " << (is_estimation_mode() ? "true" : "false") << std::endl;
  os << "   Levels         : " << (unsigned int) num_levels_ << std::endl;
  os << "   Sorted         : " << (is_level_zero_sorted_ ? "true" : "false") << std::endl;
  os << "   Capacity items : " << items_size_ << std::endl;
  os << "   Retained items : " << get_num_retained() << std::endl;
  if (!is_empty()) {
    os << "   Min item      : " << *min_item_ << std::endl;
    os << "   Max item      : " << *max_item_ << std::endl;
  }
  os << "### End sketch summary" << std::endl;

  if (print_levels) {
    os << "### KLL sketch levels:" << std::endl;
    os << "   index: nominal capacity, actual size" << std::endl;
    for (uint8_t i = 0; i < num_levels_; i++) {
      os << "   " << (unsigned int) i << ": " << kll_helper::level_capacity(k_, num_levels_, i, m_) << ", " << safe_level_size(i) << std::endl;
    }
    os << "### End sketch levels" << std::endl;
  }

  if (print_items) {
    os << "### KLL sketch data:" << std::endl;
    uint8_t level = 0;
    while (level < num_levels_) {
      const uint32_t from_index = levels_[level];
      const uint32_t to_index = levels_[level + 1]; // exclusive
      if (from_index < to_index) {
        os << " level " << (unsigned int) level << ":" << std::endl;
      }
      for (uint32_t i = from_index; i < to_index; i++) {
        os << "   " << items_[i] << std::endl;
      }
      level++;
    }
    os << "### End sketch data" << std::endl;
  }
  return string<A>(os.str().c_str(), allocator_);
}