Histogram.hpp

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/*
 * Histogram.hpp
 *
 * Histogram code to hold histogram data.
 *
 *  Created on: 14 Dec 2021
 *   Author(s): Jorn Reniers, Volkan Kumtepeli
 */
 
#pragma once
 
#include "../settings/settings.hpp"
#include "../utility/utility.hpp"
 
#include <vector>
#include <cstdlib>
#include <algorithm>
#include <span>
#include <fstream>
 
namespace slide {
 
enum class HistogramType {
  slidepack = 0,
  equidistant = 1
 
};
 
template <HistogramType histogramType = HistogramType::equidistant, typename Tdata = double>
class Histogram
{
  std::vector<size_t> bins;
  Tdata x_min{}, x_max{}, dx{ 1 };
  int Nbins;
 
public:
  Histogram() = default;
 
  Histogram(Tdata x_min_, Tdata x_max_, int Nbins_ = settings::DATASTORE_NHIST)
    : bins(Nbins_ + 2), x_min(x_min_), x_max(x_max_), dx((x_max_ - x_min_) / Nbins_), Nbins(Nbins_)
  {
  }
 
  constexpr void add(Tdata x) noexcept
  {
    /*
     * increase the correct bin counter
     * data is in bin i if edge[i-1] <= data < edge[i]
     * bins[0] is number of elements less than x_min
     * bins[end] is number of elements more than x_max
     * */
    auto i = static_cast<int>(1 + (x - x_min) / dx);
 
    const auto ssize = static_cast<int>(bins.size());
    i = std::max(0, std::min(i, ssize - 1)); // #TODO what happens if container is empty?
    bins[i]++;
  }
 
  std::span<const size_t> viewBinValues() const noexcept { return bins; }
 
  [[nodiscard]] constexpr auto begin() noexcept { return bins.begin(); }
  [[nodiscard]] constexpr auto end() noexcept { return bins.end(); }
 
  auto getEdgeValues() const noexcept { return range_fix(x_min, x_max, dx); }
 
  auto size() const noexcept { return bins.size(); }
 
  friend std::ostream &operator<<(std::ostream &ofs, const Histogram<> &hist);
};
 
inline std::ostream &operator<<(std::ostream &ofs, const Histogram<> &hist)
{
  auto bins = hist.viewBinValues();
  auto edges = hist.getEdgeValues();
 
  ofs << "Edges:\n";
 
  for (auto edge : edges)
    ofs << edge << ',';
 
  ofs << '\n';
  ofs << "Bins:\n";
 
  for (auto bin : bins)
    ofs << bin << ',';
 
  ofs << '\n';
 
  return ofs;
}
 
static Histogram<> EmptyHistogram{};
 
} // namespace slide