es.uam.eps.ir.ranksys.nn.item.sim

Class ItemSimilarity<I>

java.lang.Object

es.uam.eps.ir.ranksys.nn.item.sim.ItemSimilarity<I>

Type Parameters:

I - type of the items

All Implemented Interfaces:

ItemIndex<I>, FastItemIndex<I>, Similarity

Direct Known Subclasses:

SetCosineItemSimilarity, SetJaccardItemSimilarity, VectorCosineItemSimilarity, VectorJaccardItemSimilarity

public abstract class ItemSimilarity<I>
extends Object
implements Similarity, FastItemIndex<I>

Item similarity. It wraps a generic fast similarity and a fast item index.

Author:

Saúl Vargas (saul.vargas@uam.es)

Field Summary

Fields

Modifier and Type	Field and Description
protected FastItemIndex<I>	iIndex Fast item index.
protected Similarity	sim Generic fast similarity.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ItemSimilarity(FastItemIndex<I> iIndex, Similarity sim) Constructor.

Method Summary

Modifier and Type	Method and Description
I	iidx2item(int iidx) Returns the item represented with the index.
int	item2iidx(I i) Returns the index assigned to the item.
int	numItems() Counts the number of indexed items.
Stream<Tuple2id>	similarElems(int idx) Returns all the users/items having a similarity greater than 0, together with the value of the similarity.
Stream<Tuple2od<I>>	similarItems(I i) Returns all the items that are similar to the item.
Stream<Tuple2id>	similarItems(int iidx) Returns all the items that are similar to the item - fast version.
ToDoubleFunction<I>	similarity(I i1) Returns a function returning similarities with the item
double	similarity(I i1, I i2) Returns the similarity between a pair of items.
IntToDoubleFunction	similarity(int idx1) Returns a function that returns the similarity with the user/item.
double	similarity(int idx1, int idx2) Returns the similarity between two users/items.

Methods inherited from class java.lang.Object

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

Methods inherited from interface es.uam.eps.ir.ranksys.fast.index.FastItemIndex

containsItem, getAllIidx, getAllItems, iidx2item, iidx2item, item2iidx, item2iidx

Field Detail

iIndex

protected final FastItemIndex<I> iIndex

Fast item index.

sim

protected final Similarity sim

Generic fast similarity.

Constructor Detail

ItemSimilarity

protected ItemSimilarity(FastItemIndex<I> iIndex,
                         Similarity sim)

Constructor.

Parameters:

iIndex - fast item index

sim - generic fast similarity

Method Detail

numItems

public int numItems()

Description copied from interface: ItemIndex

Counts the number of indexed items.

Specified by:

numItems in interface ItemIndex<I>

Returns:

the total number of item

item2iidx

public int item2iidx(I i)

Description copied from interface: FastItemIndex

Returns the index assigned to the item.

Specified by:

item2iidx in interface FastItemIndex<I>

Parameters:

i - item

Returns:

the index of the item, or -1 if the item does not exist

iidx2item

public I iidx2item(int iidx)

Description copied from interface: FastItemIndex

Returns the item represented with the index.

Specified by:

iidx2item in interface FastItemIndex<I>

Parameters:

iidx - item index

Returns:

the item whose index is iidx

similarity

public ToDoubleFunction<I> similarity(I i1)

Returns a function returning similarities with the item

Parameters:

i1 - item

Returns:

a function returning similarities with the item

similarity

public double similarity(I i1,
                         I i2)

Returns the similarity between a pair of items.

Parameters:

i1 - first item

i2 - second item

Returns:

similarity value between the items

similarItems

public Stream<Tuple2od<I>> similarItems(I i)

Returns all the items that are similar to the item.

Parameters:

i - item

Returns:

a stream of item-similarity pairs

similarItems

public Stream<Tuple2id> similarItems(int iidx)

Returns all the items that are similar to the item - fast version.

Parameters:

iidx - item

Returns:

a stream of item-similarity pairs

similarity

public IntToDoubleFunction similarity(int idx1)

Description copied from interface: Similarity

Returns a function that returns the similarity with the user/item.

Specified by:

similarity in interface Similarity

Parameters:

idx1 - index of the user/item

Returns:

function that returns the similarity with the index

similarity

public double similarity(int idx1,
                         int idx2)

Description copied from interface: Similarity

Returns the similarity between two users/items.

Specified by:

similarity in interface Similarity

Parameters:

idx1 - index of user/item

idx2 - index of user/item

Returns:

similarity between the pair

similarElems

public Stream<Tuple2id> similarElems(int idx)

Description copied from interface: Similarity

Returns all the users/items having a similarity greater than 0, together with the value of the similarity.

Specified by:

similarElems in interface Similarity

Parameters:

idx - index of user/item

Returns:

stream of index-similarity pairs