我可以从Apache Spark UDF中返回Tuple2吗（在Java中）？

Question

I need a UDF2 that takes two arguments as input corresponding to two Dataframe columns of types String and mllib.linalg.Vector and return a Tuple2. IS this doable? if yes, how do I register this udf()?

hiveContext.udf().register("getItemData", get_item_data, WHAT GOES HERE FOR RETURN TYPE?);

the udf is defined as follows:

UDF2<String, org.apache.spark.mllib.linalg.Vector, Tuple2<String, org.apache.spark.mllib.linalg.Vector>> get_item_data =
            (String id, org.apache.spark.mllib.linalg.Vector features) -> {
        return new Tuple2<>(id, features);
    };

Answer 1

There goes a schema which can be defined as follows:

import org.apache.spark.sql.types.DataType;
import org.apache.spark.sql.types.DataTypes;
import org.apache.spark.mllib.linalg.VectorUDT;

List<StructField> fields = new ArrayList<>();
fields.add(DataTypes.createStructField("id", DataTypes.StringType, false));
fields.add(DataTypes.createStructField("features", new VectorUDT(), false));
DataType schema = DataTypes.createStructType(fields);

but if all you need is just a struct without any additional processing org.apache.spark.sql.functions.struct should do the trick:

df.select(struct(col("id"), col("features"));