average_calculator.h

[詳解]

 
 
// Copyright(c) 2023-2025 Design Engineering Laboratory, Saitama University
// Released under the MIT license
// https://opensource.org/licenses/mit-license.php
 
#ifndef DESIGNLAB_AVERAGE_CALCULATOR_H_
#define DESIGNLAB_AVERAGE_CALCULATOR_H_
 
#include <cmath>
#include <optional>
#include <vector>
 
 
namespace designlab
{
 
template <typename T, typename = std::enable_if_t<std::is_arithmetic<T>::value>>
class AverageCalculator final
{
public:
    AverageCalculator() :
        data_(),
        sum_(std::nullopt),
        average_(std::nullopt),
        variance_(std::nullopt),
        standard_deviation_(std::nullopt)
    {
    }
 
    void AddData(const T& data, const bool do_calc = true)
    {
        data_.push_back(data);
 
        if (sum_.has_value())
        {
            sum_ = sum_.value() + data;
        }
        else
        {
            sum_ = data;
        }
 
        if (do_calc)
        {
            Calculate();
        }
    }
 
    void Clear()
    {
        data_.clear();
        sum_ = std::nullopt;
        average_ = std::nullopt;
        variance_ = std::nullopt;
        standard_deviation_ = std::nullopt;
    }
 
    void Calculate()
    {
        // データが空の場合は，平均値，分散，標準偏差を nullopt にする．
        if (data_.empty())
        {
            average_ = std::nullopt;
            variance_ = std::nullopt;
            standard_deviation_ = std::nullopt;
            return;
        }
 
        // 平均値を求める．
        average_ = sum_.value() / data_.size();
 
        // 分散を求める．
        T variance_sum = 0;
 
        for (const auto& data : data_)
        {
            variance_sum += (data - average_.value()) * (data - average_.value());
        }
        variance_ = variance_sum / data_.size();
 
        // 標準偏差を求める．
        standard_deviation_ = sqrt(variance_.value());
    }
 
    std::optional<T> GetAverage() const
    {
        return average_;
    }
 
    std::optional<T> GetVariance() const
    {
        return variance_;
    }
 
    std::optional<T> GetStandardDeviation() const
    {
        return standard_deviation_;
    }
 
    size_t GetDataNum() const
    {
        return data_.size();
    }
 
    std::optional<T> GetSum() const
    {
        return sum_;
    }
 
private:
    std::vector<T> data_;
    std::optional<T> sum_;
    std::optional<T> average_;
    std::optional<T> variance_;
    std::optional<T> standard_deviation_;
};
 
}  // namespace designlab
 
 
#endif  // DESIGNLAB_AVERAGE_CALCULATOR_H_