ClickHouse/src/AggregateFunctions/Moments.h
2021-05-26 14:58:31 +03:00

363 lines
8.8 KiB
C++

#pragma once
#include <IO/WriteHelpers.h>
#include <IO/ReadHelpers.h>
namespace DB
{
struct Settings;
namespace ErrorCodes
{
extern const int DECIMAL_OVERFLOW;
}
/**
Calculating univariate central moments
Levels:
level 2 (pop & samp): var, stddev
level 3: skewness
level 4: kurtosis
References:
https://en.wikipedia.org/wiki/Moment_(mathematics)
https://en.wikipedia.org/wiki/Skewness
https://en.wikipedia.org/wiki/Kurtosis
*/
template <typename T, size_t _level>
struct VarMoments
{
T m[_level + 1]{};
void add(T x)
{
++m[0];
m[1] += x;
m[2] += x * x;
if constexpr (_level >= 3) m[3] += x * x * x;
if constexpr (_level >= 4) m[4] += x * x * x * x;
}
void merge(const VarMoments & rhs)
{
m[0] += rhs.m[0];
m[1] += rhs.m[1];
m[2] += rhs.m[2];
if constexpr (_level >= 3) m[3] += rhs.m[3];
if constexpr (_level >= 4) m[4] += rhs.m[4];
}
void write(WriteBuffer & buf) const
{
writePODBinary(*this, buf);
}
void read(ReadBuffer & buf)
{
readPODBinary(*this, buf);
}
T getPopulation() const
{
if (m[0] == 0)
return std::numeric_limits<T>::quiet_NaN();
/// Due to numerical errors, the result can be slightly less than zero,
/// but it should be impossible. Trim to zero.
return std::max(T{}, (m[2] - m[1] * m[1] / m[0]) / m[0]);
}
T getSample() const
{
if (m[0] <= 1)
return std::numeric_limits<T>::quiet_NaN();
return std::max(T{}, (m[2] - m[1] * m[1] / m[0]) / (m[0] - 1));
}
T getMoment3() const
{
if (m[0] == 0)
return std::numeric_limits<T>::quiet_NaN();
// to avoid accuracy problem
if (m[0] == 1)
return 0;
/// \[ \frac{1}{m_0} (m_3 - (3 * m_2 - \frac{2 * {m_1}^2}{m_0}) * \frac{m_1}{m_0});\]
return (m[3]
- (3 * m[2]
- 2 * m[1] * m[1] / m[0]
) * m[1] / m[0]
) / m[0];
}
T getMoment4() const
{
if (m[0] == 0)
return std::numeric_limits<T>::quiet_NaN();
// to avoid accuracy problem
if (m[0] == 1)
return 0;
/// \[ \frac{1}{m_0}(m_4 - (4 * m_3 - (6 * m_2 - \frac{3 * m_1^2}{m_0} ) \frac{m_1}{m_0})\frac{m_1}{m_0})\]
return (m[4]
- (4 * m[3]
- (6 * m[2]
- 3 * m[1] * m[1] / m[0]
) * m[1] / m[0]
) * m[1] / m[0]
) / m[0];
}
};
template <typename T, size_t _level>
class VarMomentsDecimal
{
public:
using NativeType = typename T::NativeType;
void add(NativeType x)
{
++m0;
getM(1) += x;
NativeType tmp;
bool overflow = common::mulOverflow(x, x, tmp) || common::addOverflow(getM(2), tmp, getM(2));
if constexpr (_level >= 3)
overflow = overflow || common::mulOverflow(tmp, x, tmp) || common::addOverflow(getM(3), tmp, getM(3));
if constexpr (_level >= 4)
overflow = overflow || common::mulOverflow(tmp, x, tmp) || common::addOverflow(getM(4), tmp, getM(4));
if (overflow)
throw Exception("Decimal math overflow", ErrorCodes::DECIMAL_OVERFLOW);
}
void merge(const VarMomentsDecimal & rhs)
{
m0 += rhs.m0;
getM(1) += rhs.getM(1);
bool overflow = common::addOverflow(getM(2), rhs.getM(2), getM(2));
if constexpr (_level >= 3)
overflow = overflow || common::addOverflow(getM(3), rhs.getM(3), getM(3));
if constexpr (_level >= 4)
overflow = overflow || common::addOverflow(getM(4), rhs.getM(4), getM(4));
if (overflow)
throw Exception("Decimal math overflow", ErrorCodes::DECIMAL_OVERFLOW);
}
void write(WriteBuffer & buf) const { writePODBinary(*this, buf); }
void read(ReadBuffer & buf) { readPODBinary(*this, buf); }
Float64 getPopulation(UInt32 scale) const
{
if (m0 == 0)
return std::numeric_limits<Float64>::infinity();
NativeType tmp;
if (common::mulOverflow(getM(1), getM(1), tmp) ||
common::subOverflow(getM(2), NativeType(tmp / m0), tmp))
throw Exception("Decimal math overflow", ErrorCodes::DECIMAL_OVERFLOW);
return std::max(Float64{}, DecimalUtils::convertTo<Float64>(T(tmp / m0), scale));
}
Float64 getSample(UInt32 scale) const
{
if (m0 == 0)
return std::numeric_limits<Float64>::quiet_NaN();
if (m0 == 1)
return std::numeric_limits<Float64>::infinity();
NativeType tmp;
if (common::mulOverflow(getM(1), getM(1), tmp) ||
common::subOverflow(getM(2), NativeType(tmp / m0), tmp))
throw Exception("Decimal math overflow", ErrorCodes::DECIMAL_OVERFLOW);
return std::max(Float64{}, DecimalUtils::convertTo<Float64>(T(tmp / (m0 - 1)), scale));
}
Float64 getMoment3(UInt32 scale) const
{
if (m0 == 0)
return std::numeric_limits<Float64>::infinity();
NativeType tmp;
if (common::mulOverflow(2 * getM(1), getM(1), tmp) ||
common::subOverflow(3 * getM(2), NativeType(tmp / m0), tmp) ||
common::mulOverflow(tmp, getM(1), tmp) ||
common::subOverflow(getM(3), NativeType(tmp / m0), tmp))
throw Exception("Decimal math overflow", ErrorCodes::DECIMAL_OVERFLOW);
return DecimalUtils::convertTo<Float64>(T(tmp / m0), scale);
}
Float64 getMoment4(UInt32 scale) const
{
if (m0 == 0)
return std::numeric_limits<Float64>::infinity();
NativeType tmp;
if (common::mulOverflow(3 * getM(1), getM(1), tmp) ||
common::subOverflow(6 * getM(2), NativeType(tmp / m0), tmp) ||
common::mulOverflow(tmp, getM(1), tmp) ||
common::subOverflow(4 * getM(3), NativeType(tmp / m0), tmp) ||
common::mulOverflow(tmp, getM(1), tmp) ||
common::subOverflow(getM(4), NativeType(tmp / m0), tmp))
throw Exception("Decimal math overflow", ErrorCodes::DECIMAL_OVERFLOW);
return DecimalUtils::convertTo<Float64>(T(tmp / m0), scale);
}
private:
UInt64 m0{};
NativeType m[_level]{};
NativeType & getM(size_t i) { return m[i - 1]; }
const NativeType & getM(size_t i) const { return m[i - 1]; }
};
/**
Calculating multivariate central moments
Levels:
level 2 (pop & samp): covar
References:
https://en.wikipedia.org/wiki/Moment_(mathematics)
*/
template <typename T>
struct CovarMoments
{
T m0{};
T x1{};
T y1{};
T xy{};
void add(T x, T y)
{
++m0;
x1 += x;
y1 += y;
xy += x * y;
}
void merge(const CovarMoments & rhs)
{
m0 += rhs.m0;
x1 += rhs.x1;
y1 += rhs.y1;
xy += rhs.xy;
}
void write(WriteBuffer & buf) const
{
writePODBinary(*this, buf);
}
void read(ReadBuffer & buf)
{
readPODBinary(*this, buf);
}
T NO_SANITIZE_UNDEFINED getPopulation() const
{
return (xy - x1 * y1 / m0) / m0;
}
T NO_SANITIZE_UNDEFINED getSample() const
{
if (m0 == 0)
return std::numeric_limits<T>::quiet_NaN();
return (xy - x1 * y1 / m0) / (m0 - 1);
}
};
template <typename T>
struct CorrMoments
{
T m0{};
T x1{};
T y1{};
T xy{};
T x2{};
T y2{};
void add(T x, T y)
{
++m0;
x1 += x;
y1 += y;
xy += x * y;
x2 += x * x;
y2 += y * y;
}
void merge(const CorrMoments & rhs)
{
m0 += rhs.m0;
x1 += rhs.x1;
y1 += rhs.y1;
xy += rhs.xy;
x2 += rhs.x2;
y2 += rhs.y2;
}
void write(WriteBuffer & buf) const
{
writePODBinary(*this, buf);
}
void read(ReadBuffer & buf)
{
readPODBinary(*this, buf);
}
T NO_SANITIZE_UNDEFINED get() const
{
return (m0 * xy - x1 * y1) / sqrt((m0 * x2 - x1 * x1) * (m0 * y2 - y1 * y1));
}
};
/// Data for calculation of Student and Welch T-Tests.
template <typename T>
struct TTestMoments
{
T nx{};
T ny{};
T x1{};
T y1{};
T x2{};
T y2{};
void addX(T value)
{
++nx;
x1 += value;
x2 += value * value;
}
void addY(T value)
{
++ny;
y1 += value;
y2 += value * value;
}
void merge(const TTestMoments & rhs)
{
nx += rhs.nx;
ny += rhs.ny;
x1 += rhs.x1;
y1 += rhs.y1;
x2 += rhs.x2;
y2 += rhs.y2;
}
void write(WriteBuffer & buf) const
{
writePODBinary(*this, buf);
}
void read(ReadBuffer & buf)
{
readPODBinary(*this, buf);
}
};
}