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0018 package org.apache.spark.examples.mllib;
0019
0020
0021 import java.util.HashMap;
0022 import java.util.Map;
0023
0024 import scala.Tuple2;
0025
0026 import org.apache.spark.SparkConf;
0027 import org.apache.spark.api.java.JavaPairRDD;
0028 import org.apache.spark.api.java.JavaRDD;
0029 import org.apache.spark.api.java.JavaSparkContext;
0030 import org.apache.spark.mllib.regression.LabeledPoint;
0031 import org.apache.spark.mllib.tree.GradientBoostedTrees;
0032 import org.apache.spark.mllib.tree.configuration.BoostingStrategy;
0033 import org.apache.spark.mllib.tree.model.GradientBoostedTreesModel;
0034 import org.apache.spark.mllib.util.MLUtils;
0035
0036
0037 public class JavaGradientBoostingRegressionExample {
0038 public static void main(String[] args) {
0039
0040 SparkConf sparkConf = new SparkConf()
0041 .setAppName("JavaGradientBoostedTreesRegressionExample");
0042 JavaSparkContext jsc = new JavaSparkContext(sparkConf);
0043
0044 String datapath = "data/mllib/sample_libsvm_data.txt";
0045 JavaRDD<LabeledPoint> data = MLUtils.loadLibSVMFile(jsc.sc(), datapath).toJavaRDD();
0046
0047 JavaRDD<LabeledPoint>[] splits = data.randomSplit(new double[]{0.7, 0.3});
0048 JavaRDD<LabeledPoint> trainingData = splits[0];
0049 JavaRDD<LabeledPoint> testData = splits[1];
0050
0051
0052
0053 BoostingStrategy boostingStrategy = BoostingStrategy.defaultParams("Regression");
0054 boostingStrategy.setNumIterations(3);
0055 boostingStrategy.getTreeStrategy().setMaxDepth(5);
0056
0057 Map<Integer, Integer> categoricalFeaturesInfo = new HashMap<>();
0058 boostingStrategy.treeStrategy().setCategoricalFeaturesInfo(categoricalFeaturesInfo);
0059
0060 GradientBoostedTreesModel model = GradientBoostedTrees.train(trainingData, boostingStrategy);
0061
0062
0063 JavaPairRDD<Double, Double> predictionAndLabel =
0064 testData.mapToPair(p -> new Tuple2<>(model.predict(p.features()), p.label()));
0065 double testMSE = predictionAndLabel.mapToDouble(pl -> {
0066 double diff = pl._1() - pl._2();
0067 return diff * diff;
0068 }).mean();
0069 System.out.println("Test Mean Squared Error: " + testMSE);
0070 System.out.println("Learned regression GBT model:\n" + model.toDebugString());
0071
0072
0073 model.save(jsc.sc(), "target/tmp/myGradientBoostingRegressionModel");
0074 GradientBoostedTreesModel sameModel = GradientBoostedTreesModel.load(jsc.sc(),
0075 "target/tmp/myGradientBoostingRegressionModel");
0076
0077
0078 jsc.stop();
0079 }
0080 }