/**
* 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.svd;
import org.apache.mahout.cf.taste.impl.TasteTestCase;
import org.apache.mahout.cf.taste.impl.common.FastByIDMap;
import org.apache.mahout.cf.taste.impl.common.FullRunningAverage;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.impl.common.RunningAverage;
import org.apache.mahout.cf.taste.impl.model.GenericDataModel;
import org.apache.mahout.cf.taste.impl.model.GenericPreference;
import org.apache.mahout.cf.taste.impl.model.GenericUserPreferenceArray;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.model.Preference;
import org.apache.mahout.cf.taste.model.PreferenceArray;
import org.apache.mahout.math.DenseVector;
import org.apache.mahout.math.Vector;
import org.junit.Before;
import org.junit.Test;
import java.util.Arrays;
public class ALSWRFactorizerTest extends TasteTestCase {
private ALSWRFactorizer factorizer;
private DataModel dataModel;
/**
* rating-matrix
*
* burger hotdog berries icecream
* dog 5 5 2 -
* rabbit 2 - 3 5
* cow - 5 - 3
* donkey 3 - - 5
*/
@Override
@Before
public void setUp() throws Exception {
super.setUp();
FastByIDMap<PreferenceArray> userData = new FastByIDMap<PreferenceArray>();
userData.put(1L, new GenericUserPreferenceArray(Arrays.asList(new GenericPreference(1L, 1L, 5.0f),
new GenericPreference(1L, 2L, 5.0f),
new GenericPreference(1L, 3L, 2.0f))));
userData.put(2L, new GenericUserPreferenceArray(Arrays.asList(new GenericPreference(2L, 1L, 2.0f),
new GenericPreference(2L, 3L, 3.0f),
new GenericPreference(2L, 4L, 5.0f))));
userData.put(3L, new GenericUserPreferenceArray(Arrays.asList(new GenericPreference(3L, 2L, 5.0f),
new GenericPreference(3L, 4L, 3.0f))));
userData.put(4L, new GenericUserPreferenceArray(Arrays.asList(new GenericPreference(4L, 1L, 3.0f),
new GenericPreference(4L, 4L, 5.0f))));
dataModel = new GenericDataModel(userData);
factorizer = new ALSWRFactorizer(dataModel, 3, 0.065, 10);
}
@Test
public void setFeatureColumn() throws Exception {
ALSWRFactorizer.Features features = new ALSWRFactorizer.Features(factorizer);
Vector vector = new DenseVector(new double[] { 0.5, 2.0, 1.5 });
int index = 1;
features.setFeatureColumnInM(index, vector);
double[][] matrix = features.getM();
assertEquals(vector.get(0), matrix[index][0], EPSILON);
assertEquals(vector.get(1), matrix[index][1], EPSILON);
assertEquals(vector.get(2), matrix[index][2], EPSILON);
}
@Test
public void ratingVector() throws Exception {
PreferenceArray prefs = dataModel.getPreferencesFromUser(1);
Vector ratingVector = factorizer.ratingVector(prefs);
assertEquals(prefs.length(), ratingVector.getNumNondefaultElements());
assertEquals(prefs.get(0).getValue(), ratingVector.get(0), EPSILON);
assertEquals(prefs.get(1).getValue(), ratingVector.get(1), EPSILON);
assertEquals(prefs.get(2).getValue(), ratingVector.get(2), EPSILON);
}
@Test
public void averageRating() throws Exception {
ALSWRFactorizer.Features features = new ALSWRFactorizer.Features(factorizer);
assertEquals(2.5, features.averateRating(3L), EPSILON);
}
@Test
public void initializeM() throws Exception {
ALSWRFactorizer.Features features = new ALSWRFactorizer.Features(factorizer);
double[][] M = features.getM();
assertEquals(3.333333333, M[0][0], EPSILON);
assertEquals(5, M[1][0], EPSILON);
assertEquals(2.5, M[2][0], EPSILON);
assertEquals(4.333333333, M[3][0], EPSILON);
for (int itemIndex = 0; itemIndex < dataModel.getNumItems(); itemIndex++) {
for (int feature = 1; feature < 3; feature++ ) {
assertTrue(M[itemIndex][feature] >= 0);
assertTrue(M[itemIndex][feature] <= 0.1);
}
}
}
@Test
public void toyExample() throws Exception {
SVDRecommender svdRecommender = new SVDRecommender(dataModel, factorizer);
/* a hold out test would be better, but this is just a toy example so we only check that the
* factorization is close to the original matrix */
RunningAverage avg = new FullRunningAverage();
LongPrimitiveIterator userIDs = dataModel.getUserIDs();
while (userIDs.hasNext()) {
long userID = userIDs.nextLong();
for (Preference pref : dataModel.getPreferencesFromUser(userID)) {
double rating = pref.getValue();
double estimate = svdRecommender.estimatePreference(userID, pref.getItemID());
double err = rating - estimate;
avg.addDatum(err * err);
}
}
double rmse = Math.sqrt(avg.getAverage());
assertTrue(rmse < 0.2);
}
}