Github user MLnick commented on a diff in the pull request:
https://github.com/apache/spark/pull/11776#discussion_r56481142
--- Diff:
examples/src/main/java/org/apache/spark/examples/mllib/JavaStreamingTestExample.java
---
@@ -0,0 +1,121 @@
+/*
+ * 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.spark.examples.mllib;
+
+
+import org.apache.spark.Accumulator;
+import org.apache.spark.api.java.function.VoidFunction;
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.function.Function;
+// $example on$
+import org.apache.spark.mllib.stat.test.BinarySample;
+import org.apache.spark.mllib.stat.test.StreamingTest;
+import org.apache.spark.mllib.stat.test.StreamingTestResult;
+// $example off$
+import org.apache.spark.SparkConf;
+import org.apache.spark.streaming.Duration;
+import org.apache.spark.streaming.Seconds;
+import org.apache.spark.streaming.api.java.JavaDStream;
+import org.apache.spark.streaming.api.java.JavaStreamingContext;
+import org.apache.spark.util.Utils;
+
+
+/**
+ * Perform streaming testing using Welch's 2-sample t-test on a stream of
data, where the data
+ * stream arrives as text files in a directory. Stops when the two groups
are statistically
+ * significant (p-value < 0.05) or after a user-specified timeout in
number of batches is exceeded.
+ *
+ * The rows of the text files must be in the form `Boolean, Double`. For
example:
+ * false, -3.92
+ * true, 99.32
+ *
+ * Usage:
+ * JavaStreamingTestExample <dataDir> <batchDuration> <numBatchesTimeout>
+ *
+ * To run on your local machine using the directory `dataDir` with 5
seconds between each batch and
+ * a timeout after 100 insignificant batches, call:
+ * $ bin/run-example mllib.JavaStreamingTestExample dataDir 5 100
+ *
+ * As you add text files to `dataDir` the significance test wil
continually update every
+ * `batchDuration` seconds until the test becomes significant (p-value <
0.05) or the number of
+ * batches processed exceeds `numBatchesTimeout`.
+ */
+public class JavaStreamingTestExample {
+ public static void main(String[] args) {
+ if (args.length != 3) {
+ System.err.println("Usage: JavaStreamingTestExample " +
+ "<dataDir> <batchDuration> <numBatchesTimeout>");
+ System.exit(1);
+ }
+
+ String dataDir = args[0];
+ Duration batchDuration = Seconds.apply(Long.valueOf(args[1]));
+ int numBatchesTimeout = Integer.valueOf(args[2]);
+
+ SparkConf conf = new
SparkConf().setMaster("local").setAppName("StreamingTestExample");
+ JavaStreamingContext ssc = new JavaStreamingContext(conf,
batchDuration);
+
+
ssc.checkpoint(Utils.createTempDir(System.getProperty("java.io.tmpdir"),
"spark").toString());
+
+ // $example on$
+ JavaDStream<BinarySample> data = ssc.textFileStream(dataDir).map(
+ new Function<String, BinarySample>() {
+ @Override
+ public BinarySample call(String line) throws Exception {
+ String[] ts = line.split(",");
+ boolean label = Boolean.valueOf(ts[0]);
+ double value = Double.valueOf(ts[1]);
+ return new BinarySample(label, value);
+ }
+ });
+
+ StreamingTest streamingTest = new StreamingTest()
+ .setPeacePeriod(0)
+ .setWindowSize(0)
+ .setTestMethod("welch");
+
+ JavaDStream<StreamingTestResult> out =
streamingTest.registerStream(data);
+ out.print();
+ // $example off$
+
+ // Stop processing if test becomes significant or we time out
+ final Accumulator<Integer> timeoutCounter =
+ ssc.sparkContext().accumulator(numBatchesTimeout);
+
+ out.foreachRDD(new VoidFunction<JavaRDD<StreamingTestResult>>() {
+ @Override
+ public void call(JavaRDD<StreamingTestResult> rdd) throws Exception {
+ timeoutCounter.add(-1);
+
+ long cntSignificant = rdd.filter(new Function<StreamingTestResult,
Boolean>() {
+ @Override
+ public Boolean call(StreamingTestResult v) throws Exception {
--- End diff --
`Utils.createTempDir` uses default args so args are required in Java.
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