/**
* 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.model.DataModel;
import org.apache.mahout.cf.taste.model.Preference;
import org.apache.mahout.cf.taste.model.PreferenceArray;
import org.junit.Test;
/** <p>Tests {@link InverseUserFrequency}.</p> */
public final class InverseUserFrequencyTest extends TransformTestCase {
@Test
public void testIUF() throws Exception {
DataModel dataModel = getDataModel(
new long[] {1, 2, 3, 4, 5},
new Double[][] {
{0.1},
{0.2, 0.3},
{0.4, 0.5, 0.6},
{0.7, 0.8, 0.9, 1.0},
{1.0, 1.0, 1.0, 1.0, 1.0},
});
InverseUserFrequency iuf = new InverseUserFrequency(dataModel, 10.0);
PreferenceArray user5Prefs = dataModel.getPreferencesFromUser(5);
for (int i = 0; i < 5; i++) {
Preference pref = user5Prefs.get(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);
}
}