Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.mahout.cf.taste.recommender; import java.util.List; import org.apache.mahout.cf.taste.common.TasteException; import org.apache.mahout.common.LongPair; /** * <p> * Interface implemented by "item-based" recommenders. * </p> */ public interface ItemBasedRecommender extends Recommender { /** * @param itemID * ID of item for which to find most similar other items * @param howMany * desired number of most similar items to find * @return items most similar to the given item, ordered from most similar to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> mostSimilarItems(long itemID, int howMany) throws TasteException; /** * @param itemID * ID of item for which to find most similar other items * @param howMany * desired number of most similar items to find * @param rescorer * {@link Rescorer} which can adjust item-item similarity estimates used to determine most similar * items * @return itemss most similar to the given item, ordered from most similar to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> mostSimilarItems(long itemID, int howMany, Rescorer<LongPair> rescorer) throws TasteException; /** * @param itemIDs * IDs of item for which to find most similar other items * @param howMany * desired number of most similar items to find estimates used to determine most similar items * @return items most similar to the given items, ordered from most similar to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> mostSimilarItems(long[] itemIDs, int howMany) throws TasteException; /** * @param itemIDs * IDs of item for which to find most similar other items * @param howMany * desired number of most similar items to find * @param rescorer * {@link Rescorer} which can adjust item-item similarity estimates used to determine most similar * items * @return items most similar to the given items, ordered from most similar to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> mostSimilarItems(long[] itemIDs, int howMany, Rescorer<LongPair> rescorer) throws TasteException; /** * @param itemIDs * IDs of item for which to find most similar other items * @param howMany * desired number of most similar items to find * @param excludeItemIfNotSimilarToAll * exclude an item if it is not similar to each of the input items * @return items most similar to the given items, ordered from most similar to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> mostSimilarItems(long[] itemIDs, int howMany, boolean excludeItemIfNotSimilarToAll) throws TasteException; /** * @param itemIDs * IDs of item for which to find most similar other items * @param howMany * desired number of most similar items to find * @param rescorer * {@link Rescorer} which can adjust item-item similarity estimates used to determine most similar * items * @param excludeItemIfNotSimilarToAll * exclude an item if it is not similar to each of the input items * @return items most similar to the given items, ordered from most similar to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> mostSimilarItems(long[] itemIDs, int howMany, Rescorer<LongPair> rescorer, boolean excludeItemIfNotSimilarToAll) throws TasteException; /** * <p> * Lists the items that were most influential in recommending a given item to a given user. Exactly how this * is determined is left to the implementation, but, generally this will return items that the user prefers * and that are similar to the given item. * </p> * * <p> * This returns a {@link List} of {@link RecommendedItem} which is a little misleading since it's returning * recommend<strong>ing</strong> items, but, I thought it more natural to just reuse this class since it * encapsulates an item and value. The value here does not necessarily have a consistent interpretation or * expected range; it will be higher the more influential the item was in the recommendation. * </p> * * @param userID * ID of user who was recommended the item * @param itemID * ID of item that was recommended * @param howMany * maximum number of items to return * @return {@link List} of {@link RecommendedItem}, ordered from most influential in recommended the given * item to least * @throws TasteException * if an error occurs while accessing the {@link org.apache.mahout.cf.taste.model.DataModel} */ List<RecommendedItem> recommendedBecause(long userID, long itemID, int howMany) throws TasteException; }