org.grouplens.lenskit.data.pref

Class Preferences

java.lang.Object

org.grouplens.lenskit.data.pref.Preferences

public final class Preferences
extends Object

Utility class for working with preferences.

Method Summary

Modifier and Type	Method and Description
static boolean	equals(Preference p1, Preference p2) Compare two preferences for equality.
static int	hashPreference(Preference preference) Compute the hash code of a preference.
static Preference	make(long uid, long iid, double val) Create a new preference.
static PreferenceBuilder	newBuilder() Construct a new preference builder.
static MutableSparseVector	userPreferenceVector(Collection<? extends Preference> prefs) Compute a user preference vector.

Methods inherited from class java.lang.Object

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

Method Detail

newBuilder

public static PreferenceBuilder newBuilder()

Construct a new preference builder.

Returns:

A new preference builder.

make

public static Preference make(long uid,
                              long iid,
                              double val)

Create a new preference.

Parameters:

uid - The user ID.

iid - The item ID.

val - The value.

Returns:

A preference with the specified properties.

userPreferenceVector

public static MutableSparseVector userPreferenceVector(Collection<? extends Preference> prefs)

Compute a user preference vector.

Parameters:

prefs - The user's preferences.

Returns:

A vector of the preferences.

Throws:

IllegalArgumentException - if the same item appears multiple times, or there are preferences from multiple users.

hashPreference

public static int hashPreference(Preference preference)

Compute the hash code of a preference. Used to implement Object.hashCode() in preference implementations.

Parameters:

preference - The preference.

Returns:

The preference's hash code.

equals

public static boolean equals(Preference p1,
                             Preference p2)

Compare two preferences for equality. Used to implement Object.equals(Object) in preference implementations.

Parameters:

p1 - The first preference.

p2 - The second preference.

Returns:

Whether the two preferences are equal.