org.lenskit.api

Interface ItemBasedItemRecommender

All Known Implementing Classes:

AbstractItemBasedItemRecommender, PopularItemRecommender, TopNItemBasedItemRecommender

public interface ItemBasedItemRecommender

Recommends items that go with a set of reference items. This interface is distinguished from ItemRecommender in that it uses a set of reference items instead of a user as the basis for computing scores.

Since:

0.10

See Also:

ItemRecommender

Compatibility

Public

Method Summary

Modifier and Type	Method and Description
java.util.List<java.lang.Long>	recommendRelatedItems(long reference) Recommend all possible items for a reference item using the default exclude set.
java.util.List<java.lang.Long>	recommendRelatedItems(long reference, int n) Recommend up to n possible items for a reference item using the default exclude set.
java.util.List<java.lang.Long>	recommendRelatedItems(java.util.Set<java.lang.Long> basket) Recommend all possible items for a set of reference items using the default exclude set.
java.util.List<java.lang.Long>	recommendRelatedItems(java.util.Set<java.lang.Long> basket, int n) Recommend up to n items for a set of reference items using the default exclude set.
java.util.List<java.lang.Long>	recommendRelatedItems(java.util.Set<java.lang.Long> basket, int n, java.util.Set<java.lang.Long> candidates, java.util.Set<java.lang.Long> exclude) Produce a set of recommendations for the item.
ResultList	recommendRelatedItemsWithDetails(java.util.Set<java.lang.Long> basket, int n, java.util.Set<java.lang.Long> candidates, java.util.Set<java.lang.Long> exclude) Produce a set of recommendations for the item, with details.

Method Detail

recommendRelatedItems

java.util.List<java.lang.Long> recommendRelatedItems(long reference)

Recommend all possible items for a reference item using the default exclude set.

Parameters:

reference - The reference item.

Returns:

The recommended items.

See Also:

recommendRelatedItems(Set, int, Set, Set)

recommendRelatedItems

java.util.List<java.lang.Long> recommendRelatedItems(long reference,
                                                     int n)

Recommend up to n possible items for a reference item using the default exclude set.

Parameters:

reference - The reference item.

n - The number of items to recommend. If negative, recommend as many as possible.

Returns:

The recommended items.

See Also:

recommendRelatedItems(Set, int, Set, Set)

recommendRelatedItems

java.util.List<java.lang.Long> recommendRelatedItems(java.util.Set<java.lang.Long> basket)

Recommend all possible items for a set of reference items using the default exclude set.

Parameters:

basket - The reference items.

Returns:

The recommended items.

See Also:

recommendRelatedItems(Set, int, Set, Set)

recommendRelatedItems

java.util.List<java.lang.Long> recommendRelatedItems(java.util.Set<java.lang.Long> basket,
                                                     int n)

Recommend up to n items for a set of reference items using the default exclude set.

Parameters:

basket - The reference items.

n - The number of recommendations to return. If negative, recommend as many as possible.

Returns:

The recommended items.

See Also:

recommendRelatedItems(Set, int, Set, Set)

recommendRelatedItems

java.util.List<java.lang.Long> recommendRelatedItems(java.util.Set<java.lang.Long> basket,
                                                     int n,
                                                     @Nullable
                                                     java.util.Set<java.lang.Long> candidates,
                                                     @Nullable
                                                     java.util.Set<java.lang.Long> exclude)

Produce a set of recommendations for the item. This is the most general recommendation method, allowing the recommendations to be constrained by both a candidate set \(\mathcal{C}\) and an exclude set \(\mathcal{E}\). The exclude set is applied to the candidate set, so the final effective candidate set is \(\mathcal{C} \backslash \mathcal{E}\).

The recommender is not guaranteed to return a full n recommendations. There are many reasons why it might return a shorter list, including lack of items, lack of coverage for items, or a predefined notion of a maximum recommendation list length. However, a negative value for n instructs the recommender to return as many as it can consistent with any limitations built in to its design and/or supporting algorithms.

Parameters:

basket - The reference items.

n - The number of ratings to return. If negative, recommend as many as possible.

candidates - A set of candidate items which can be recommended. If null, all items are considered candidates.

exclude - A set of items to be excluded. If null, a default exclude set is used.

Returns:

A list of recommended items.

recommendRelatedItemsWithDetails

ResultList recommendRelatedItemsWithDetails(java.util.Set<java.lang.Long> basket,
                                            int n,
                                            @Nullable
                                            java.util.Set<java.lang.Long> candidates,
                                            @Nullable
                                            java.util.Set<java.lang.Long> exclude)

Produce a set of recommendations for the item, with details. This method functions identically to recommendRelatedItems(Set, int, Set, Set), except that it returns more detailed results.

Parameters:

basket - The reference items.

n - The number of ratings to return. If negative, recommend as many as possible.

candidates - A set of candidate items which can be recommended. If null, all items are considered candidates.

exclude - A set of items to be excluded. If null, a default exclude set is used.

Returns:

A list of recommended items with recommendation details. If the recommender cannot assign meaningful scores, the scores will be Double.NaN.