package org.apache.mahout.math.hadoop.stats;
/**
* 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.
*/
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.mahout.common.MahoutTestCase;
import org.apache.mahout.common.RandomUtils;
import org.apache.mahout.math.jet.random.Normal;
import org.junit.Before;
import org.junit.Test;
import java.util.Random;
public final class BasicStatsTest extends MahoutTestCase {
private Configuration conf;
@Override
@Before
public void setUp() throws Exception {
super.setUp();
conf = getConfiguration();
}
@Test
public void testVar() throws Exception {
Path input = getTestTempFilePath("stdDev/counts.file");
Path output = getTestTempFilePath("stdDev/output.file");
produceTestData(input);
double v = BasicStats.variance(input, output, conf);
assertEquals(2.44, v, 0.01);
}
@Test
public void testStdDev() throws Exception {
Path input = getTestTempFilePath("stdDev/counts.file");
Path output = getTestTempFilePath("stdDev/output.file");
produceTestData(input);
double v = BasicStats.stdDev(input, output, conf);
assertEquals(1.56, v, 0.01); //sample std dev is 1.563, std. dev from a discrete set is 1.48
}
@Test
public void testStdDevForGivenMean() throws Exception {
Path input = getTestTempFilePath("stdDev/counts.file");
Path output = getTestTempFilePath("stdDev/output.file");
produceTestData(input);
double v = BasicStats.stdDevForGivenMean(input, output, 0.0D, conf);
assertEquals(10.65, v, 0.01); //sample std dev is 10.65
}
private void produceTestData(Path input) throws Exception {
FileSystem fs = FileSystem.get(input.toUri(), conf);
SequenceFile.Writer writer = new SequenceFile.Writer(fs, conf, input, IntWritable.class, DoubleWritable.class);
//Random random = new MersenneTwisterRNG();
/*Normal normal = new Normal(5, 3, random);
for (int i = 0; i < 10000; i++) {
writer.append(new IntWritable(i), new DoubleWritable((long)normal.nextDouble()));
}*/
int i = 0;
writer.append(new IntWritable(i++), new DoubleWritable(7));
writer.append(new IntWritable(i++), new DoubleWritable(9));
writer.append(new IntWritable(i++), new DoubleWritable(9));
writer.append(new IntWritable(i++), new DoubleWritable(10));
writer.append(new IntWritable(i++), new DoubleWritable(10));
writer.append(new IntWritable(i++), new DoubleWritable(10));
writer.append(new IntWritable(i++), new DoubleWritable(10));
writer.append(new IntWritable(i++), new DoubleWritable(11));
writer.append(new IntWritable(i++), new DoubleWritable(11));
writer.append(new IntWritable(i++), new DoubleWritable(13));
writer.close();
}
//Not entirely sure on this test
@Test
public void testStdDev2() throws Exception {
Path input = getTestTempFilePath("stdDev/counts.file");
Path output = getTestTempFilePath("stdDev/output.file");
FileSystem fs = FileSystem.get(input.toUri(), conf);
SequenceFile.Writer writer = new SequenceFile.Writer(fs, conf, input, IntWritable.class,
DoubleWritable.class);
Random random = RandomUtils.getRandom();
Normal normal = new Normal(5, 3, random);
for (int i = 0; i < 1000000; i++) {
writer.append(new IntWritable(i), new DoubleWritable((long) normal.nextInt()));
}
writer.close();
double v = BasicStats.stdDev(input, output, conf);
assertEquals(3, v, 0.02);
}
}