/**
* 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.eval;
/**
* <p>
* Implementations encapsulate information retrieval-related statistics about a
* {@link org.apache.mahout.cf.taste.recommender.Recommender}'s recommendations.
* </p>
*
* <p>
* See <a href="http://en.wikipedia.org/wiki/Information_retrieval">Information retrieval</a>.
* </p>
*/
public interface IRStatistics {
/**
* <p>
* See <a href="http://en.wikipedia.org/wiki/Information_retrieval#Precision">Precision</a>.
* </p>
*/
double getPrecision();
/**
* <p>
* See <a href="http://en.wikipedia.org/wiki/Information_retrieval#Recall">Recall</a>.
* </p>
*/
double getRecall();
/**
* <p>
* See <a href="http://en.wikipedia.org/wiki/Information_retrieval#Fall-Out">Fall-Out</a>.
* </p>
*/
double getFallOut();
/**
* <p>
* See <a href="http://en.wikipedia.org/wiki/Information_retrieval#F-measure">F-measure</a>.
* </p>
*/
double getF1Measure();
/**
* <p>
* See <a href="http://en.wikipedia.org/wiki/Information_retrieval#F-measure">F-measure</a>.
* </p>
*/
double getFNMeasure(double n);
/**
* <p>
* See <a href="http://en.wikipedia.org/wiki/Discounted_cumulative_gain#Normalized_DCG">
* Normalized Discounted Cumulative Gain</a>.
* </p>
*/
double getNormalizedDiscountedCumulativeGain();
/**
* @return the fraction of all users for whom recommendations could be produced
*/
double getReach();
}