IterationWithChainingITCase.java example

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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 *
 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.flink.test.iterative;

import org.apache.flink.api.common.functions.GroupReduceFunction;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.IterativeDataSet;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.test.util.PointFormatter;
import org.apache.flink.test.util.PointInFormat;
import org.apache.flink.test.util.CoordVector;
import org.apache.flink.test.util.JavaProgramTestBase;
import org.apache.flink.util.Collector;

public class IterationWithChainingITCase extends JavaProgramTestBase {

	private static final String DATA_POINTS = "0|50.90|16.20|72.08|\n" + "1|73.65|61.76|62.89|\n" + "2|61.73|49.95|92.74|\n";

	private String dataPath;
	private String resultPath;

	@Override
	protected void preSubmit() throws Exception {
		dataPath = createTempFile("data_points.txt", DATA_POINTS);
		resultPath = getTempFilePath("result");
	}

	@Override
	protected void testProgram() throws Exception {
		ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
		env.setParallelism(4);

		DataSet<Tuple2<Integer, CoordVector>> initialInput
				= env.readFile(new PointInFormat(), dataPath).setParallelism(1).name("Input");

		IterativeDataSet<Tuple2<Integer, CoordVector>> iteration = initialInput.iterate(2).name("Loop");

		DataSet<Tuple2<Integer, CoordVector>> identity
				= iteration.groupBy(0).reduceGroup(new GroupReduceFunction<Tuple2<Integer, CoordVector>, Tuple2<Integer, CoordVector>>() {
					@Override
					public void reduce(Iterable<Tuple2<Integer, CoordVector>> values, Collector<Tuple2<Integer, CoordVector>> out) throws Exception {
						for (Tuple2<Integer, CoordVector> value : values) {
							out.collect(value);
						}
					}
				}).map(new MapFunction<Tuple2<Integer, CoordVector>, Tuple2<Integer, CoordVector>>() {
					@Override
					public Tuple2<Integer, CoordVector> map(Tuple2<Integer, CoordVector> value) throws Exception {
						return value;
					}

				});

		iteration.closeWith(identity).writeAsFormattedText(resultPath, new PointFormatter());

		env.execute("Iteration with chained map test");

		compareResultsByLinesInMemory(DATA_POINTS, resultPath);
	}
}