org.grouplens.lenskit.vectors

Class Vectors

java.lang.Object

org.grouplens.lenskit.vectors.Vectors

public final class Vectors
extends Object

Utility methods for interacting with vectors.

Compatibility

Public

Method Summary

Modifier and Type	Method and Description
static Iterable<org.apache.commons.lang3.tuple.Pair<VectorEntry,VectorEntry>>	fastIntersect(SparseVector v1, SparseVector v2) Iterate over the intersection of two vectors without the overhead of object creation.
static MutableSparseVector	fromArray(IdIndexMapping map, double[] values) Create a mutable sparse vector from an array and index mapping.
static MutableSparseVector	fromScoredIds(List<ScoredId> scores)
static Iterable<org.apache.commons.lang3.tuple.ImmutablePair<VectorEntry,VectorEntry>>	intersect(SparseVector v1, SparseVector v2) Iterate over the intersection of two vectors - they keys they have in common.

Methods inherited from class java.lang.Object

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

Method Detail

fromScoredIds

public static MutableSparseVector fromScoredIds(List<ScoredId> scores)

fromArray

public static MutableSparseVector fromArray(IdIndexMapping map,
                                            double[] values)

Create a mutable sparse vector from an array and index mapping.

Parameters:

map - The index mapping specifying the keys.

values - The array of values.

Returns:

A sparse vector mapping the IDs in map to the values in values.

Throws:

IllegalArgumentException - if values not the same size as map.

intersect

public static Iterable<org.apache.commons.lang3.tuple.ImmutablePair<VectorEntry,VectorEntry>> intersect(SparseVector v1,
                                                                                                        SparseVector v2)

Iterate over the intersection of two vectors - they keys they have in common.

Parameters:

v1 - The first vector.

v2 - The second vector.

Returns:

An iterator over the common pairs. This iterator will never contain null entries.

fastIntersect

public static Iterable<org.apache.commons.lang3.tuple.Pair<VectorEntry,VectorEntry>> fastIntersect(SparseVector v1,
                                                                                                   SparseVector v2)

Iterate over the intersection of two vectors without the overhead of object creation.

Parameters:

v1 - The first vector.

v2 - The second vector.

Returns:

A fast iterator over the common keys of the two vectors.

See Also:

intersect(SparseVector, SparseVector)