/**
* 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.similarity;
import com.google.common.base.Preconditions;
import org.apache.mahout.cf.taste.common.Refreshable;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.common.FastIDSet;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.impl.common.RefreshHelper;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.similarity.ItemSimilarity;
import java.util.Collection;
public abstract class AbstractItemSimilarity implements ItemSimilarity {
private final DataModel dataModel;
private final RefreshHelper refreshHelper;
protected AbstractItemSimilarity(DataModel dataModel) {
Preconditions.checkArgument(dataModel != null, "dataModel is null");
this.dataModel = dataModel;
this.refreshHelper = new RefreshHelper(null);
refreshHelper.addDependency(this.dataModel);
}
protected DataModel getDataModel() {
return dataModel;
}
@Override
public long[] allSimilarItemIDs(long itemID) throws TasteException {
FastIDSet allSimilarItemIDs = new FastIDSet();
LongPrimitiveIterator allItemIDs = dataModel.getItemIDs();
while (allItemIDs.hasNext()) {
long possiblySimilarItemID = allItemIDs.nextLong();
if (!Double.isNaN(itemSimilarity(itemID, possiblySimilarItemID))) {
allSimilarItemIDs.add(possiblySimilarItemID);
}
}
return allSimilarItemIDs.toArray();
}
@Override
public void refresh(Collection<Refreshable> alreadyRefreshed) {
refreshHelper.refresh(alreadyRefreshed);
}
}