Stats.hxx

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#ifndef _UTILS_STATS_HXX_
#define _UTILS_STATS_HXX_
 
#include <math.h>
#include <stdint.h>
#include <string>
#include <limits>
 
class Stats
{
public:
    using FloatType = double;
    using ValueType = int32_t;
 
    Stats()
    {
        clear();
    }
 
    // Clear the statistics (erase all data points).
    void clear()
    {
        sum_ = 0;
        count_ = 0;
        qsum_ = 0;
        max_ = std::numeric_limits<ValueType>::min();
    }
 
    void add(ValueType value)
    {
        ++count_;
        sum_ += value;
        FloatType fval = value;
        qsum_ += fval * fval;
        if (value > max_)
        {
            max_ = value;
        }
    }
 
    FloatType favg()
    {
        return FloatType(sum_) / count_;
    }
 
    int32_t avg()
    {
        return sum_ / count_;
    }
 
    FloatType stddev()
    {
        // Formula: sqrt(N*qsum - sum^2) / N
        FloatType sum(sum_);
        return sqrt(qsum_ * count_ - sum * sum) / count_;
    }
 
    std::string debug_string();
 
private:
    uint32_t count_;
    ValueType max_;
    int64_t sum_;
    FloatType qsum_;
};
 
#endif // _UTILS_STATS_HXX_