为什么Spark失败并且"值rdf不是org.apache.spark.sql.SparkSession的成员"？

Question

我正在尝试使用SANSA-RDF将海龟RDF文件读入Spark并创建图形.我执行以下代码时收到错误.我错过了什么？

    import org.apache.jena.query.QueryFactory
    import org.apache.jena.riot.Lang
    import org.apache.spark.sql.SparkSession
    import net.sansa_stack.rdf.spark.io.rdf._
    import net.sansa_stack.rdf.spark.io._
    import scala.io.Source

    object SparkExecutor {
      private var ss:SparkSession = null

      def ConfigureSpark(): Unit ={

        ss = SparkSession.builder
          .master("local[*]")
          .config("spark.driver.cores", 1)
          .appName("LAM")
          .getOrCreate()

      }

      def createGraph(): Unit ={
        val filename = "xyz.ttl"
        print("Loading graph from file"+ filename)
        val lang = Lang.TTL
        val triples = ss.rdf(lang)(filename)
        val graph = LoadGraph(triples)    
      }
    }

我正在使用main函数调用SparkExecutor

    object main {
      def main(args: Array[String]): Unit = {
        SparkExecutor.ConfigureSpark()
        val RDFGraph = SparkExecutor.createGraph()
      }
    }

这会导致以下错误

    Error: value rdf is not a member of org.apache.spark.sql.SparkSession
val triples = ss.rdf(lang)

Answer 1

如果你看到SANSA-RDF源代码,那么有一个隐式转换

sansa-rdf-spark/src/main/scala/net/sansa_stack/rdf/spark/io/package.scala:159

rdf(lang)不是spark会话的方法,而是隐式类RDFReader的方法,因此您需要导入隐式定义可用的包.请尝试添加

import net.sansa_stack.rdf.spark.io._

让我们知道结果.