org.apache.mahout.cf.taste.impl.recommender.NullRescorer Maven / Gradle / Ivy
/**
* 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 org.apache.mahout.cf.taste.recommender.IDRescorer;
import org.apache.mahout.cf.taste.recommender.Rescorer;
import org.apache.mahout.common.LongPair;
/**
*
* A simple {@link Rescorer} which always returns the original score.
*
*/
public final class NullRescorer implements Rescorer, IDRescorer {
private static final IDRescorer USER_OR_ITEM_INSTANCE = new NullRescorer();
private static final Rescorer ITEM_ITEM_PAIR_INSTANCE = new NullRescorer<>();
private static final Rescorer USER_USER_PAIR_INSTANCE = new NullRescorer<>();
private NullRescorer() {
}
public static IDRescorer getItemInstance() {
return USER_OR_ITEM_INSTANCE;
}
public static IDRescorer getUserInstance() {
return USER_OR_ITEM_INSTANCE;
}
public static Rescorer getItemItemPairInstance() {
return ITEM_ITEM_PAIR_INSTANCE;
}
public static Rescorer getUserUserPairInstance() {
return USER_USER_PAIR_INSTANCE;
}
/**
* @param thing
* to rescore
* @param originalScore
* current score for item
* @return same originalScore as new score, always
*/
@Override
public double rescore(T thing, double originalScore) {
return originalScore;
}
@Override
public boolean isFiltered(T thing) {
return false;
}
@Override
public double rescore(long id, double originalScore) {
return originalScore;
}
@Override
public boolean isFiltered(long id) {
return false;
}
@Override
public String toString() {
return "NullRescorer";
}
}