NgramDemo.java

package com.topsec.ti.patronus;
import java.util.Arrays;
import java.util.List;

import org.apache.spark.ml.feature.NGram;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.RowFactory;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.sql.types.DataTypes;
import org.apache.spark.sql.types.Metadata;
import org.apache.spark.sql.types.StructField;
import org.apache.spark.sql.types.StructType;

/**
 * Created by hhy on 2017/09/06.
 */
public class NgramDemo {
    public static void main(String[] args){
        SparkSession spark= SparkSession.builder().master("local").appName("").getOrCreate();
//        List<Row> data = Arrays.asList(
//                RowFactory.create(0, Arrays.asList("Hi", "I", "heard", "about", "Spark")),
//                RowFactory.create(1, Arrays.asList("I", "wish", "Java", "could", "use", "case", "classes")),
//                RowFactory.create(2, Arrays.asList("Logistic", "regression", "models", "are", "neat"))
//        );
        List<Row> data = Arrays.asList(
                RowFactory.create("I have"),
                RowFactory.create("I have one"),
                RowFactory.create("I have tow")
        );
//
//        StructType schema = new StructType(new StructField[]{
//                new StructField("id", DataTypes.IntegerType, false, Metadata.empty()),
//                new StructField(
//                        "words", DataTypes.createArrayType(DataTypes.StringType), false, Metadata.empty())
//        });
        StructType schema = new StructType(new StructField[]{
                new StructField("words", DataTypes.StringType, false, Metadata.empty())
        });

        Dataset<Row> wordDataFrame = spark.createDataFrame(data, schema);
        wordDataFrame.show();

        NGram ngramTransformer = new NGram().setN(3).setInputCol("words").setOutputCol("ngrams");

        Dataset<Row> ngramDataFrame = ngramTransformer.transform(wordDataFrame);
        ngramDataFrame.select("ngrams").show(false);
    }
}