/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.grouplens.lenskit.vectors.similarity;
import org.grouplens.lenskit.vectors.MutableSparseVector;
import org.grouplens.lenskit.vectors.SparseVector;
import org.junit.Test;
import static org.grouplens.lenskit.vectors.similarity.SpearmanRankCorrelation.rank;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
/**
* @author <a href="http://www.grouplens.org">GroupLens Research</a>
*/
public class SpearmanRankCorrelationTest {
@Test
public void testRankEmpty() {
assertTrue(rank(MutableSparseVector.create()).isEmpty());
}
@Test
public void testRankSingle() {
SparseVector v = MutableSparseVector.wrap(new long[]{1}, new double[]{5});
SparseVector r = rank(v);
assertEquals(1, r.size());
assertEquals(1, r.get(1), 1.0e-6);
}
@Test
public void testRankSeveral() {
long[] keys = {1, 2, 3, 4, 5};
double[] values = {7, 2, 3, 1, 5};
SparseVector v = MutableSparseVector.wrap(keys, values).freeze();
SparseVector r = rank(v);
assertEquals(5, r.size());
assertEquals(1, r.get(1), 1.0e-6);
assertEquals(2, r.get(5), 1.0e-6);
assertEquals(3, r.get(3), 1.0e-6);
assertEquals(4, r.get(2), 1.0e-6);
assertEquals(5, r.get(4), 1.0e-6);
}
@Test
public void testRankTie() {
long[] keys = {1, 2, 3, 4, 5};
double[] values = {7, 2, 3, 1, 3};
SparseVector v = MutableSparseVector.wrap(keys, values).freeze();
SparseVector r = rank(v);
assertEquals(5, r.size());
assertEquals(1, r.get(1), 1.0e-6);
assertEquals(2.5, r.get(3), 1.0e-6);
assertEquals(2.5, r.get(5), 1.0e-6);
assertEquals(4, r.get(2), 1.0e-6);
assertEquals(5, r.get(4), 1.0e-6);
}
}