/**
* 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 com.google.common.collect.Lists;
import org.apache.mahout.cf.taste.common.TasteException;
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.FastIDSet;
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.cf.taste.recommender.CandidateItemsStrategy;
import org.junit.Test;
import java.util.List;
/**
* Tests {@link SamplingCandidateItemsStrategy}
*/
public final class SamplingCandidateItemsStrategyTest extends TasteTestCase {
@Test
public void testStrategy() throws TasteException {
List<Preference> prefsOfUser123 = Lists.newArrayList();
prefsOfUser123.add(new GenericPreference(123L, 1L, 1.0f));
List<Preference> prefsOfUser456 = Lists.newArrayList();
prefsOfUser456.add(new GenericPreference(456L, 1L, 1.0f));
prefsOfUser456.add(new GenericPreference(456L, 2L, 1.0f));
List<Preference> prefsOfUser789 = Lists.newArrayList();
prefsOfUser789.add(new GenericPreference(789L, 1L, 0.5f));
prefsOfUser789.add(new GenericPreference(789L, 3L, 1.0f));
PreferenceArray prefArrayOfUser123 = new GenericUserPreferenceArray(prefsOfUser123);
FastByIDMap<PreferenceArray> userData = new FastByIDMap<PreferenceArray>();
userData.put(123L, prefArrayOfUser123);
userData.put(456L, new GenericUserPreferenceArray(prefsOfUser456));
userData.put(789L, new GenericUserPreferenceArray(prefsOfUser789));
DataModel dataModel = new GenericDataModel(userData);
CandidateItemsStrategy strategy =
new SamplingCandidateItemsStrategy(1, 1, 1, dataModel.getNumUsers(), dataModel.getNumItems());
FastIDSet candidateItems = strategy.getCandidateItems(123L, prefArrayOfUser123, dataModel);
/* result can be either item2 or item3 or empty */
assertTrue(candidateItems.size() <= 1);
assertFalse(candidateItems.contains(1L));
}
}