com.cloudera.oryx.app.als

Class ALSUtils

java.lang.Object

com.cloudera.oryx.app.als.ALSUtils

public final class ALSUtils
extends Object

ALS-related utility methods for the app tier.

Method Summary

Modifier and Type	Method and Description
static double	computeTargetQui(boolean implicit, double value, double currentValue) Computes how the estimated strength of interaction in the model should change -- to what target value -- in response to a new interaction.
static float[]	computeUpdatedXu(Solver solver, double value, float[] Xu, float[] Yi, boolean implicit) Computes how a user vector Xu changes in response to interaction with an item vector Yi.

Methods inherited from class java.lang.Object

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

Method Detail

computeTargetQui

public static double computeTargetQui(boolean implicit,
                                      double value,
                                      double currentValue)

Computes how the estimated strength of interaction in the model should change -- to what target value -- in response to a new interaction.

Parameters:

implicit - whether the model is implicit feedback

value - new interaction's strength

currentValue - existing estimated of strength of interaction

Returns:

new target estimated of strength of interaction, or NaN to signal "no change needed"

computeUpdatedXu

public static float[] computeUpdatedXu(Solver solver,
                                       double value,
                                       float[] Xu,
                                       float[] Yi,
                                       boolean implicit)

Computes how a user vector Xu changes in response to interaction with an item vector Yi. This can also be used to compute how an item vector changes in response to a user interaction, even though the code naming follows the former convention.

Parameters:

solver - solver helping solve for Xu in Qu*Y = Xu * (Yt * Y)

value - strength of interaction

Xu - current user vector (null if no existing user vector)

Yi - current item vector

implicit - whether the model is implicit feedback

Returns:

new user vector Xu, or null if no update should be made (i.e. there was no item vector; the update would push the new Qui farther out of range)