org.grouplens.lenskit.transform.normalize

Class AbstractVectorNormalizer

java.lang.Object

org.grouplens.lenskit.transform.normalize.AbstractVectorNormalizer

All Implemented Interfaces:

VectorNormalizer

Direct Known Subclasses:

IdentityVectorNormalizer, MeanCenteringVectorNormalizer, MeanVarianceNormalizer, UnitVectorNormalizer

public abstract class AbstractVectorNormalizer
extends Object
implements VectorNormalizer

Abstract vector normalizer implementation.

Constructor Summary

Constructors

Constructor and Description
AbstractVectorNormalizer()

Method Summary

Modifier and Type	Method and Description
MutableSparseVector	normalize(SparseVector reference, MutableSparseVector target) Normalize a vector in-place with a reference vector.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.grouplens.lenskit.transform.normalize.VectorNormalizer

makeTransformation

Constructor Detail

AbstractVectorNormalizer

public AbstractVectorNormalizer()

Method Detail

normalize

public MutableSparseVector normalize(@Nonnull
                                     SparseVector reference,
                                     @Nullable
                                     MutableSparseVector target)

Normalize a vector in-place with a reference vector.

To understand the relationship of reference and vector, consider wanting to subtract the user's mean rating from a set of ratings. To do that, the user's rating vector is reference, and the vector of ratings to be adjusted is vector.

This method is equivalent to makeTransformation(reference).apply(target).

Delegates to VectorNormalizer.makeTransformation(SparseVector) and the resulting VectorTransformation.

Specified by:

normalize in interface VectorNormalizer

Parameters:

reference - The reference used to compute whatever transformation is needed (e.g. the mean value).

target - The vector to normalize. If null, a new mutable copy of reference is created.

Returns:

target, or a normalized mutable copy of reference if target is null.