/**
* 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.transforms;
import org.apache.mahout.cf.taste.impl.model.GenericDataModel;
import org.apache.mahout.cf.taste.model.Preference;
import org.apache.mahout.cf.taste.model.User;
import java.util.ArrayList;
import java.util.List;
/**
* <p>Tests {@link InverseUserFrequency}.</p>
*/
public final class InverseUserFrequencyTest extends TransformTestCase {
public void testIUF() throws Exception {
List<User> users = new ArrayList<User>(5);
users.add(getUser("test1", 0.1));
users.add(getUser("test2", 0.2, 0.3));
users.add(getUser("test3", 0.4, 0.5, 0.6));
users.add(getUser("test4", 0.7, 0.8, 0.9, 1.0));
users.add(getUser("test5", 1.0, 1.0, 1.0, 1.0, 1.0));
GenericDataModel dummy = new GenericDataModel(users);
InverseUserFrequency iuf = new InverseUserFrequency(dummy, 10.0);
User user = dummy.getUser("test5");
for (int i = 0; i < 5; i++) {
Preference pref = user.getPreferenceFor(String.valueOf(i));
assertNotNull(pref);
assertEquals(Math.log(5.0 / (double) (5 - i)) / Math.log(iuf.getLogBase()),
iuf.getTransformedValue(pref),
EPSILON);
}
// Make sure this doesn't throw an exception
iuf.refresh(null);
}
}