我想将spark中的结构体传递给udf。它正在更改字段名称并将其重命名为列位置。我如何解决它?在UDF中获得更改的Spark Struct结构体域名称
object TestCSV {
def main(args: Array[String]) {
val conf = new SparkConf().setAppName("localTest").setMaster("local")
val sc = new SparkContext(conf)
val sqlContext = new SQLContext(sc)
val inputData = sqlContext.read.format("com.databricks.spark.csv")
.option("delimiter","|")
.option("header", "true")
.load("test.csv")
inputData.printSchema()
inputData.show()
val groupedData = inputData.withColumn("name",struct(inputData("firstname"),inputData("lastname")))
val udfApply = groupedData.withColumn("newName",processName(groupedData("name")))
udfApply.show()
}
def processName = udf((input:Row) =>{
println(input)
println(input.schema)
Map("firstName" -> input.getAs[String]("firstname"), "lastName" -> input.getAs[String]("lastname"))
})
}
输出:
root
|-- id: string (nullable = true)
|-- firstname: string (nullable = true)
|-- lastname: string (nullable = true)
+---+---------+--------+
| id|firstname|lastname|
+---+---------+--------+
| 1| jack| reacher|
| 2| john| Doe|
+---+---------+--------+
错误:
[jack,reacher] StructType(StructField(i[1],StringType,true), > StructField(i[2],StringType,true)) 17/03/08 09:45:35 ERROR Executor: Exception in task 0.0 in stage 2.0 (TID 2) java.lang.IllegalArgumentException: Field "firstname" does not exist.
为什么不直接在udf中传递两个字符串(作为'字符串')? –
这是可能的,但你不能在Spark UDF中传递超过10个字段作为参数。我在这里提供的是一个简化的用例。有时我必须在UDF中传递20多列。我如何实现这一目标? – hp2326