Statistics.h

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/*
 * OpenVINS: An Open Platform for Visual-Inertial Research
 * Copyright (C) 2018-2023 Patrick Geneva
 * Copyright (C) 2018-2023 Guoquan Huang
 * Copyright (C) 2018-2023 OpenVINS Contributors
 * Copyright (C) 2018-2019 Kevin Eckenhoff
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef OV_EVAL_STATISTICS_H
#define OV_EVAL_STATISTICS_H

#include <fstream>
#include <iostream>
#include <string>

#include <Eigen/Eigen>

namespace ov_eval {

struct Statistics {

public:
  double rmse = 0.0;

  double mean = 0.0;

  double median = 0.0;

  double std = 0.0;

  double max = 0.0;

  double min = 0.0;

  double ninetynine = 0.0;

  std::vector<double> timestamps;

  std::vector<double> values;

  std::vector<double> values_bound;

  void calculate() {

    // Sort the data for easy finding of values
    std::vector<double> values_sorted = values;
    std::sort(values_sorted.begin(), values_sorted.end());

    // If we don't have any data, just return :(
    if (values_sorted.empty())
      return;

    // Now that its been sorted, can easily grab min and max
    min = values_sorted.at(0);
    max = values_sorted.at(values_sorted.size() - 1);

    // Compute median
    // ODD:  grab middle from the sorted vector
    // EVEN: average the middle two numbers
    if (values_sorted.size() == 1) {
      median = values_sorted.at(values_sorted.size() - 1);
    } else if (values_sorted.size() % 2 == 1) {
      median = values_sorted.at(values_sorted.size() / 2);
    } else if (values_sorted.size() > 1) {
      median = 0.5 * (values_sorted.at(values_sorted.size() / 2 - 1) + values_sorted.at(values_sorted.size() / 2));
    } else {
      median = 0.0;
    }

    // Compute mean and rmse
    mean = 0;
    for (size_t i = 0; i < values_sorted.size(); i++) {
      assert(!std::isnan(values_sorted.at(i)));
      mean += values_sorted.at(i);
      rmse += values_sorted.at(i) * values_sorted.at(i);
    }
    mean /= values_sorted.size();
    rmse = std::sqrt(rmse / values_sorted.size());

    // Using mean, compute standard deviation
    std = 0;
    for (size_t i = 0; i < values_sorted.size(); i++) {
      std += std::pow(values_sorted.at(i) - mean, 2);
    }
    std = std::sqrt(std / (values_sorted.size() - 1));

    // 99th percentile
    // TODO: is this correct?
    // TODO: http://sphweb.bumc.bu.edu/otlt/MPH-Modules/BS/BS704_Probability/BS704_Probability10.html
    ninetynine = mean + 2.326 * std;
  }

  void clear() {
    timestamps.clear();
    values.clear();
    values_bound.clear();
  }
};

} // namespace ov_eval

#endif // OV_EVAL_STATISTICS_H