com.planetj.taste.impl.correlation
Class SpearmanCorrelation

java.lang.Object
  com.planetj.taste.impl.correlation.SpearmanCorrelation

All Implemented Interfaces:

Refreshable, UserCorrelation

public final class SpearmanCorrelation
extends java.lang.Object
implements UserCorrelation

Like PearsonCorrelation, but compares relative ranking of preference values instead of preference values themselves. That is, each User's preferences are sorted and then assign a rank as their preference value, with 1 being assigned to the least preferred item. Then the Pearson itemCorrelation of these rank values is computed.

Author:

Sean Owen

Constructor Summary

SpearmanCorrelation(DataModel dataModel)

SpearmanCorrelation(UserCorrelation rankingUserCorrelation)

Method Summary

void	refresh() Triggers "refresh" -- whatever that means -- of the implementation.
void	setPreferenceInferrer(PreferenceInferrer inferrer) Attaches a PreferenceInferrer to the UserCorrelation implementation.
double	userCorrelation(User user1, User user2) Returns the "itemCorrelation", or degree of similarity, of two Users, based on the their preferences.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SpearmanCorrelation

public SpearmanCorrelation(DataModel dataModel)

SpearmanCorrelation

public SpearmanCorrelation(UserCorrelation rankingUserCorrelation)

Method Detail

userCorrelation

public double userCorrelation(User user1,
                              User user2)
                       throws TasteException

Returns the "itemCorrelation", or degree of similarity, of two Users, based on the their preferences.

Specified by:

userCorrelation in interface UserCorrelation

Parameters:

user1 - first user

user2 - second user

Returns:

itemCorrelation between the two users

Throws:

TasteException - if an error occurs while accessing the data

setPreferenceInferrer

public void setPreferenceInferrer(PreferenceInferrer inferrer)

Attaches a PreferenceInferrer to the UserCorrelation implementation.

Specified by:

setPreferenceInferrer in interface UserCorrelation

Parameters:

inferrer - PreferenceInferrer

refresh

public void refresh()

Triggers "refresh" -- whatever that means -- of the implementation. The general contract is that any Refreshable should always leave itself in a consistent, operational state, and that the refresh atomically updates internal state from old to new.

Specified by:

refresh in interface Refreshable