org.apache.mahout.cf.taste.impl.similarity

Class GenericUserSimilarity

java.lang.Object

org.apache.mahout.cf.taste.impl.similarity.GenericUserSimilarity

All Implemented Interfaces:

Refreshable, UserSimilarity

public final class GenericUserSimilarity
extends Object
implements UserSimilarity

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GenericUserSimilarity.UserUserSimilarity

Constructor Summary

Constructors

Constructor and Description
GenericUserSimilarity(Iterable<GenericUserSimilarity.UserUserSimilarity> similarities)
GenericUserSimilarity(Iterable<GenericUserSimilarity.UserUserSimilarity> similarities, int maxToKeep)
GenericUserSimilarity(UserSimilarity otherSimilarity, DataModel dataModel)
GenericUserSimilarity(UserSimilarity otherSimilarity, DataModel dataModel, int maxToKeep)

Method Summary

Modifier and Type	Method and Description
void	refresh(Collection<Refreshable> alreadyRefreshed) Triggers "refresh" -- whatever that means -- of the implementation.
void	setPreferenceInferrer(PreferenceInferrer inferrer) Attaches a PreferenceInferrer to the UserSimilarity implementation.
double	userSimilarity(long userID1, long userID2) Returns the 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

GenericUserSimilarity

public GenericUserSimilarity(Iterable<GenericUserSimilarity.UserUserSimilarity> similarities)

GenericUserSimilarity

public GenericUserSimilarity(Iterable<GenericUserSimilarity.UserUserSimilarity> similarities,
                             int maxToKeep)

GenericUserSimilarity

public GenericUserSimilarity(UserSimilarity otherSimilarity,
                             DataModel dataModel)
                      throws TasteException

Throws:

TasteException

GenericUserSimilarity

public GenericUserSimilarity(UserSimilarity otherSimilarity,
                             DataModel dataModel,
                             int maxToKeep)
                      throws TasteException

Throws:

TasteException

Method Detail

userSimilarity

public double userSimilarity(long userID1,
                             long userID2)

Description copied from interface: UserSimilarity

Returns the degree of similarity, of two users, based on the their preferences.

Specified by:

userSimilarity in interface UserSimilarity

Parameters:

userID1 - first user ID

userID2 - second user ID

Returns:

similarity between the users, in [-1,1] or Double.NaN similarity is unknown

setPreferenceInferrer

public void setPreferenceInferrer(PreferenceInferrer inferrer)

Description copied from interface: UserSimilarity

Attaches a PreferenceInferrer to the UserSimilarity implementation.

Specified by:

setPreferenceInferrer in interface UserSimilarity

Parameters:

inferrer - PreferenceInferrer

refresh

public void refresh(Collection<Refreshable> alreadyRefreshed)

Description copied from interface: Refreshable

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

Parameters:

alreadyRefreshed - Refreshables that are known to have already been refreshed as a result of an initial call to a {#refresh(Collection)} method on some object. This ensure that objects in a refresh dependency graph aren't refreshed twice needlessly.