/**
* 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.
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package org.apache.mahout.cf.taste.impl.recommender.svd;
import org.apache.mahout.cf.taste.impl.TasteTestCase;
import org.apache.mahout.cf.taste.impl.common.FastIDSet;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.model.PreferenceArray;
import org.apache.mahout.cf.taste.recommender.CandidateItemsStrategy;
import org.apache.mahout.cf.taste.recommender.RecommendedItem;
import org.easymock.EasyMock;
import org.junit.Test;
import java.util.List;
public class SVDRecommenderTest extends TasteTestCase {
@Test
public void estimatePreference() throws Exception {
DataModel dataModel = EasyMock.createMock(DataModel.class);
Factorizer factorizer = EasyMock.createMock(Factorizer.class);
Factorization factorization = EasyMock.createMock(Factorization.class);
EasyMock.expect(factorizer.factorize()).andReturn(factorization);
EasyMock.expect(factorization.getUserFeatures(1L)).andReturn(new double[] { 0.4, 2 });
EasyMock.expect(factorization.getItemFeatures(5L)).andReturn(new double[] { 1, 0.3 });
EasyMock.replay(dataModel, factorizer, factorization);
SVDRecommender svdRecommender = new SVDRecommender(dataModel, factorizer);
float estimate = svdRecommender.estimatePreference(1L, 5L);
assertEquals(1, estimate, EPSILON);
EasyMock.verify(dataModel, factorizer, factorization);
}
@Test
public void recommend() throws Exception {
DataModel dataModel = EasyMock.createMock(DataModel.class);
PreferenceArray preferencesFromUser = EasyMock.createMock(PreferenceArray.class);
CandidateItemsStrategy candidateItemsStrategy = EasyMock.createMock(CandidateItemsStrategy.class);
Factorizer factorizer = EasyMock.createMock(Factorizer.class);
Factorization factorization = EasyMock.createMock(Factorization.class);
FastIDSet candidateItems = new FastIDSet();
candidateItems.add(5L);
candidateItems.add(3L);
EasyMock.expect(factorizer.factorize()).andReturn(factorization);
EasyMock.expect(dataModel.getPreferencesFromUser(1L)).andReturn(preferencesFromUser);
EasyMock.expect(candidateItemsStrategy.getCandidateItems(1L, preferencesFromUser, dataModel))
.andReturn(candidateItems);
EasyMock.expect(factorization.getUserFeatures(1L)).andReturn(new double[] { 0.4, 2 });
EasyMock.expect(factorization.getItemFeatures(5L)).andReturn(new double[] { 1, 0.3 });
EasyMock.expect(factorization.getUserFeatures(1L)).andReturn(new double[] { 0.4, 2 });
EasyMock.expect(factorization.getItemFeatures(3L)).andReturn(new double[] { 2, 0.6 });
EasyMock.replay(dataModel, candidateItemsStrategy, factorizer, factorization);
SVDRecommender svdRecommender = new SVDRecommender(dataModel, factorizer, candidateItemsStrategy);
List<RecommendedItem> recommendedItems = svdRecommender.recommend(1L, 5);
assertEquals(2, recommendedItems.size());
assertEquals(3L, recommendedItems.get(0).getItemID());
assertEquals(2.0f, recommendedItems.get(0).getValue(), EPSILON);
assertEquals(5L, recommendedItems.get(1).getItemID());
assertEquals(1.0f, recommendedItems.get(1).getValue(), EPSILON);
EasyMock.verify(dataModel, candidateItemsStrategy, factorizer, factorization);
}
}