org.lenskit.eval.traintest.metrics

Class ExponentialDiscount

java.lang.Object

org.lenskit.eval.traintest.metrics.ExponentialDiscount

All Implemented Interfaces:

Discount

public class ExponentialDiscount
extends Object
implements Discount

Exponential (half-life) discounting.

Constructor Summary

Constructors

Constructor and Description
ExponentialDiscount(double hl) Construct an exponential discount.

Method Summary

Modifier and Type	Method and Description
double	discount(int rank) Compute the discount for a rank.
boolean	equals(Object o)
double	getHalfLife() Get the half-life of the discount function.
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

ExponentialDiscount

public ExponentialDiscount(double hl)

Construct an exponential discount.

Parameters:

hl - The half-life.

Method Detail

getHalfLife

public double getHalfLife()

Get the half-life of the discount function.

Returns:

The half-life of the discount function.

discount

public double discount(int rank)

Description copied from interface: Discount

Compute the discount for a rank.

Specified by:

discount in interface Discount

Parameters:

rank - The rank (with the first item having rank 1).

Returns:

The discount. This discount will be multiplied by the value, so it should generally go towards 0 as the rank increases.

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