org.apache.mahout.cf.taste.impl.common

Interface RunningAverage

All Known Subinterfaces:

RunningAverageAndStdDev

All Known Implementing Classes:

FixedRunningAverage, FixedRunningAverageAndStdDev, FullRunningAverage, FullRunningAverageAndStdDev, InvertedRunningAverage, InvertedRunningAverageAndStdDev, WeightedRunningAverage, WeightedRunningAverageAndStdDev

public interface RunningAverage

Interface for classes that can keep track of a running average of a series of numbers. One can add to or remove from the series, as well as update a datum in the series. The class does not actually keep track of the series of values, just its running average, so it doesn't even matter if you remove/change a value that wasn't added.

Method Summary

Modifier and Type	Method and Description
void	addDatum(double datum)
void	changeDatum(double delta)
double	getAverage()
int	getCount()
RunningAverage	inverse()
void	removeDatum(double datum)

Method Detail

addDatum

void addDatum(double datum)

Parameters:

datum - new item to add to the running average

Throws:

IllegalArgumentException - if datum is Double.NaN

removeDatum

void removeDatum(double datum)

Parameters:

datum - item to remove to the running average

Throws:

IllegalArgumentException - if datum is Double.NaN

IllegalStateException - if count is 0

changeDatum

void changeDatum(double delta)

Parameters:

delta - amount by which to change a datum in the running average

Throws:

IllegalArgumentException - if delta is Double.NaN

IllegalStateException - if count is 0

getCount

int getCount()

getAverage

double getAverage()

inverse

RunningAverage inverse()

Returns:

a (possibly immutable) object whose average is the negative of this object's