org.tribuo.util

Class MeanVarianceAccumulator

java.lang.Object

org.tribuo.util.MeanVarianceAccumulator

All Implemented Interfaces:

Serializable

public final class MeanVarianceAccumulator
extends Object
implements Serializable

An accumulator for online calculation of the mean and variance of a stream of doubles.

Note this class is not thread safe.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
MeanVarianceAccumulator() Constructs an empty mean/variance accumulator.
MeanVarianceAccumulator(double[] values) Constructs a mean/variance accumulator and observes the supplied array.
MeanVarianceAccumulator(MeanVarianceAccumulator other) Copy constructor.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
long	getCount() Gets the observation count.
double	getMax() Gets the maximum observed value.
double	getMean() Gets the sample mean.
double	getMin() Gets the minimum observed value.
double	getStdDev() Gets the sample standard deviation.
double	getVariance() Gets the sample variance.
int	hashCode()
void	observe(double value) Observes a value, i.e., updates the sufficient statistics for computing mean, variance, max and min.
void	observe(double[] values) Observes a value, i.e., updates the sufficient statistics for computing mean, variance, max and min.
void	reset() Resets this accumulator to the starting state.
double[]	standardize(double[] input) Standardizes the input using the computed mean and variance in this accumulator.
void	standardizeInPlace(double[] input) Standardizes the input using the computed mean and variance in this accumulator.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

MeanVarianceAccumulator

public MeanVarianceAccumulator()

Constructs an empty mean/variance accumulator.

MeanVarianceAccumulator

public MeanVarianceAccumulator(double[] values)

Constructs a mean/variance accumulator and observes the supplied array.

Parameters:

values - The array to operate on.

MeanVarianceAccumulator

public MeanVarianceAccumulator(MeanVarianceAccumulator other)

Copy constructor.

Parameters:

other - The MeanVarianceAccumulator to copy.

Method Detail

reset

public void reset()

Resets this accumulator to the starting state.

observe

public void observe(double value)

Observes a value, i.e., updates the sufficient statistics for computing mean, variance, max and min.

Parameters:

value - The value to observe.

observe

public void observe(double[] values)

Observes a value, i.e., updates the sufficient statistics for computing mean, variance, max and min.

Parameters:

values - The values to observe.

getMin

public double getMin()

Gets the minimum observed value.

Returns:

The minimum value.

getMax

public double getMax()

Gets the maximum observed value.

Returns:

The maximum value.

getMean

public double getMean()

Gets the sample mean.

Returns:

The sample mean.

getVariance

public double getVariance()

Gets the sample variance.

Returns:

The sample variance.

getCount

public long getCount()

Gets the observation count.

Returns:

The observation count.

getStdDev

public double getStdDev()

Gets the sample standard deviation.

Returns:

The sample standard deviation.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

standardize

public double[] standardize(double[] input)

Standardizes the input using the computed mean and variance in this accumulator. Standardization means subtracting the mean and dividing by the variance.

Parameters:

input - The input to standardize.

Returns:

The standardized input.

standardizeInPlace

public void standardizeInPlace(double[] input)

Standardizes the input using the computed mean and variance in this accumulator. Standardization means subtracting the mean and dividing by the variance.

Parameters:

input - The input to standardize.