/**
* 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.impl.recommender;
import com.google.common.base.Preconditions;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.common.FastIDSet;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.similarity.ItemSimilarity;
/**
* returns the result of {@link ItemSimilarity#allSimilarItemIDs(long)} as candidate items
*/
public class AllSimilarItemsCandidateItemsStrategy extends AbstractCandidateItemsStrategy {
private final ItemSimilarity similarity;
public AllSimilarItemsCandidateItemsStrategy(ItemSimilarity similarity) {
Preconditions.checkArgument(similarity != null, "similarity is null");
this.similarity = similarity;
}
@Override
protected FastIDSet doGetCandidateItems(long[] preferredItemIDs, DataModel dataModel, boolean includeKnownItems)
throws TasteException {
FastIDSet candidateItemIDs = new FastIDSet();
for (long itemID : preferredItemIDs) {
candidateItemIDs.addAll(similarity.allSimilarItemIDs(itemID));
}
if (!includeKnownItems) {
candidateItemIDs.removeAll(preferredItemIDs);
}
return candidateItemIDs;
}
}