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0018 package org.apache.spark.examples.ml;
0019
0020 import org.apache.spark.sql.SparkSession;
0021
0022
0023 import java.util.Arrays;
0024 import java.util.List;
0025
0026 import org.apache.spark.ml.feature.BucketedRandomProjectionLSH;
0027 import org.apache.spark.ml.feature.BucketedRandomProjectionLSHModel;
0028 import org.apache.spark.ml.linalg.Vector;
0029 import org.apache.spark.ml.linalg.Vectors;
0030 import org.apache.spark.ml.linalg.VectorUDT;
0031 import org.apache.spark.sql.Dataset;
0032 import org.apache.spark.sql.Row;
0033 import org.apache.spark.sql.RowFactory;
0034 import org.apache.spark.sql.types.DataTypes;
0035 import org.apache.spark.sql.types.Metadata;
0036 import org.apache.spark.sql.types.StructField;
0037 import org.apache.spark.sql.types.StructType;
0038
0039 import static org.apache.spark.sql.functions.col;
0040
0041
0042
0043
0044
0045
0046
0047 public class JavaBucketedRandomProjectionLSHExample {
0048 public static void main(String[] args) {
0049 SparkSession spark = SparkSession
0050 .builder()
0051 .appName("JavaBucketedRandomProjectionLSHExample")
0052 .getOrCreate();
0053
0054
0055 List<Row> dataA = Arrays.asList(
0056 RowFactory.create(0, Vectors.dense(1.0, 1.0)),
0057 RowFactory.create(1, Vectors.dense(1.0, -1.0)),
0058 RowFactory.create(2, Vectors.dense(-1.0, -1.0)),
0059 RowFactory.create(3, Vectors.dense(-1.0, 1.0))
0060 );
0061
0062 List<Row> dataB = Arrays.asList(
0063 RowFactory.create(4, Vectors.dense(1.0, 0.0)),
0064 RowFactory.create(5, Vectors.dense(-1.0, 0.0)),
0065 RowFactory.create(6, Vectors.dense(0.0, 1.0)),
0066 RowFactory.create(7, Vectors.dense(0.0, -1.0))
0067 );
0068
0069 StructType schema = new StructType(new StructField[]{
0070 new StructField("id", DataTypes.IntegerType, false, Metadata.empty()),
0071 new StructField("features", new VectorUDT(), false, Metadata.empty())
0072 });
0073 Dataset<Row> dfA = spark.createDataFrame(dataA, schema);
0074 Dataset<Row> dfB = spark.createDataFrame(dataB, schema);
0075
0076 Vector key = Vectors.dense(1.0, 0.0);
0077
0078 BucketedRandomProjectionLSH mh = new BucketedRandomProjectionLSH()
0079 .setBucketLength(2.0)
0080 .setNumHashTables(3)
0081 .setInputCol("features")
0082 .setOutputCol("hashes");
0083
0084 BucketedRandomProjectionLSHModel model = mh.fit(dfA);
0085
0086
0087 System.out.println("The hashed dataset where hashed values are stored in the column 'hashes':");
0088 model.transform(dfA).show();
0089
0090
0091
0092
0093
0094 System.out.println("Approximately joining dfA and dfB on distance smaller than 1.5:");
0095 model.approxSimilarityJoin(dfA, dfB, 1.5, "EuclideanDistance")
0096 .select(col("datasetA.id").alias("idA"),
0097 col("datasetB.id").alias("idB"),
0098 col("EuclideanDistance")).show();
0099
0100
0101
0102
0103
0104 System.out.println("Approximately searching dfA for 2 nearest neighbors of the key:");
0105 model.approxNearestNeighbors(dfA, key, 2).show();
0106
0107
0108 spark.stop();
0109 }
0110 }