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   * 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.
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  package org.apache.spark.mllib.stat;
  
  import java.util.Arrays;
  import java.util.List;
  
  import org.junit.After;
  import org.junit.Before;
  import org.junit.Test;
  import static org.junit.Assert.assertEquals;
  
  import org.apache.spark.SparkConf;
  import org.apache.spark.api.java.JavaDoubleRDD;
  import org.apache.spark.api.java.JavaRDD;
  import org.apache.spark.api.java.JavaSparkContext;
  import org.apache.spark.mllib.linalg.Vectors;
  import org.apache.spark.mllib.regression.LabeledPoint;
  import org.apache.spark.mllib.stat.test.BinarySample;
  import org.apache.spark.mllib.stat.test.ChiSqTestResult;
  import org.apache.spark.mllib.stat.test.KolmogorovSmirnovTestResult;
  import org.apache.spark.mllib.stat.test.StreamingTest;
  import org.apache.spark.sql.SparkSession;
  import org.apache.spark.streaming.Duration;
  import org.apache.spark.streaming.api.java.JavaDStream;
  import org.apache.spark.streaming.api.java.JavaStreamingContext;
  import static org.apache.spark.streaming.JavaTestUtils.*;
  
  public class JavaStatisticsSuite {
    private transient SparkSession spark;
    private transient JavaSparkContext jsc;
    private transient JavaStreamingContext ssc;
  
    @Before
    public void setUp() {
      SparkConf conf = new SparkConf()
        .set("spark.streaming.clock", "org.apache.spark.util.ManualClock");
      spark = SparkSession.builder()
        .master("local[2]")
        .appName("JavaStatistics")
        .config(conf)
        .getOrCreate();
      jsc = new JavaSparkContext(spark.sparkContext());
      ssc = new JavaStreamingContext(jsc, new Duration(1000));
      ssc.checkpoint("checkpoint");
    }
  
    @After
    public void tearDown() {
      spark.stop();
      ssc.stop();
      spark = null;
    }
  
    @Test
    public void testCorr() {
      JavaRDD<Double> x = jsc.parallelize(Arrays.asList(1.0, 2.0, 3.0, 4.0));
      JavaRDD<Double> y = jsc.parallelize(Arrays.asList(1.1, 2.2, 3.1, 4.3));
  
      Double corr1 = Statistics.corr(x, y);
      Double corr2 = Statistics.corr(x, y, "pearson");
      // Check default method
      assertEquals(corr1, corr2, 1e-5);
    }
  
    @Test
    public void kolmogorovSmirnovTest() {
      JavaDoubleRDD data = jsc.parallelizeDoubles(Arrays.asList(0.2, 1.0, -1.0, 2.0));
      KolmogorovSmirnovTestResult testResult1 = Statistics.kolmogorovSmirnovTest(data, "norm");
      KolmogorovSmirnovTestResult testResult2 = Statistics.kolmogorovSmirnovTest(
        data, "norm", 0.0, 1.0);
    }
  
    @Test
    public void chiSqTest() {
      JavaRDD<LabeledPoint> data = jsc.parallelize(Arrays.asList(
        new LabeledPoint(0.0, Vectors.dense(0.1, 2.3)),
        new LabeledPoint(1.0, Vectors.dense(1.5, 5.1)),
        new LabeledPoint(0.0, Vectors.dense(2.4, 8.1))));
      ChiSqTestResult[] testResults = Statistics.chiSqTest(data);
    }
  
    @Test
    public void streamingTest() {
      List<BinarySample> trainingBatch = Arrays.asList(
        new BinarySample(true, 1.0),
        new BinarySample(false, 2.0));
      JavaDStream<BinarySample> training =
        attachTestInputStream(ssc, Arrays.asList(trainingBatch, trainingBatch), 2);
      int numBatches = 2;
      StreamingTest model = new StreamingTest()
        .setWindowSize(0)
        .setPeacePeriod(0)
        .setTestMethod("welch");
      model.registerStream(training);
      attachTestOutputStream(training);
      runStreams(ssc, numBatches, numBatches);
    }
  }
  