spark MLlib collaborativeFilltering学习

package ML.collaborativeFilltering;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaDoubleRDD;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.mllib.recommendation.ALS;
import org.apache.spark.mllib.recommendation.MatrixFactorizationModel;
import org.apache.spark.mllib.recommendation.Rating;
import scala.Tuple2;

/**
 * TODO
 *
 * @ClassName: example
 * @author: DingH
 * @since: 2019/4/10 16:03
 */
public class example {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf().setAppName("Java Collaborative Filtering Example");
        JavaSparkContext jsc = new JavaSparkContext(conf);

        // Load and parse the data
        String path = "D:\IdeaProjects\SimpleApp\src\main\resources\data\mllib\als\test.data";
        JavaRDD<String> data = jsc.textFile(path);
        JavaRDD<Rating> ratings = data.map(new Function<String, Rating>() {
            public Rating call(String s) {
                String[] sarray = s.split(",");
                return new Rating(Integer.parseInt(sarray[0]), Integer.parseInt(sarray[1]), Double.parseDouble(sarray[2]));
            }
          }
        );
        int ranks = 10;
        int numIterations = 10;
        MatrixFactorizationModel model = ALS.train(ratings.rdd(), ranks, numIterations);

        JavaRDD<Tuple2<Object, Object>> userProducts = ratings.map(new Function<Rating, Tuple2<Object, Object>>() {
            public Tuple2<Object, Object> call(Rating r) {
              return new Tuple2<Object, Object>(r.user(), r.product());
            }
          }
        );
        JavaPairRDD<Tuple2<Integer, Integer>, Double> predictions = JavaPairRDD.fromJavaRDD(model.predict(JavaRDD.toRDD(userProducts)).toJavaRDD().map(
            new Function<Rating, Tuple2<Tuple2<Integer, Integer>, Double>>() {
              public Tuple2<Tuple2<Integer, Integer>, Double> call(Rating r){
                return new Tuple2<Tuple2<Integer, Integer>, Double>(
                  new Tuple2<Integer, Integer>(r.user(), r.product()), r.rating());
              }
            }
          ));

        JavaRDD<Tuple2<Double, Double>> ratesAndPreds = JavaPairRDD.fromJavaRDD(ratings.map(
            new Function<Rating, Tuple2<Tuple2<Integer, Integer>, Double>>() {
              public Tuple2<Tuple2<Integer, Integer>, Double> call(Rating r){
                return new Tuple2<Tuple2<Integer, Integer>, Double>(
                  new Tuple2<Integer, Integer>(r.user(), r.product()), r.rating());
              }
            }
          )).join(predictions).values();

        double MSE = JavaDoubleRDD.fromRDD(ratesAndPreds.map(
          new Function<Tuple2<Double, Double>, Object>() {
            public Object call(Tuple2<Double, Double> pair) {
              Double err = pair._1() - pair._2();
              return err * err;
            }
          }
        ).rdd()).mean();

        System.out.println("Mean Squared Error = " + MSE);




    }
}