我想转换RDD在Spark2.0转换RDD到数据帧在2.0
val conf=new SparkConf().setAppName("dataframes").setMaster("local")
val sc=new SparkContext(conf)
val sqlCon=new SQLContext(sc)
import sqlCon.implicits._
val rdd=sc.textFile("/home/cloudera/alpha.dat").persist()
val row=rdd.first()
val data=rdd.filter { x => !x.contains(row) }
data.foreach { x => println(x) }
case class person(name:String,age:Int,city:String)
val rdd2=data.map { x => x.split(",") }
val rdd3=rdd2.map { x => person(x(0),x(1).toInt,x(2)) }
val df=rdd3.toDF()
df.printSchema();
df.registerTempTable("alpha")
val df1=sqlCon.sql("select * from alpha")
df1.foreach { x => println(x) }
到数据帧,但在toDF我得到一个错误以下()。 ---> “VAL DF = rdd3.toDF()”
Multiple markers at this line:
- Unable to find encoder for type stored in a Dataset. Primitive types (Int, String, etc) and Product types (case
classes) are supported by importing spark.implicits._ Support for serializing other types will be added in future releases.
- Implicit conversion found: rdd3 ⇒ rddToDatasetHolder(rdd3): (implicit evidence$4:
org.apache.spark.sql.Encoder[person])org.apache.spark.sql.DatasetHolder[person]
如何以上使用toDF()
感谢埃里克。我下面https://spark.apache.org/docs/2.0.0-preview/sql-programming-guide.html#datasets为RDD转化为Dataframes 进口sqlContext.implicits._,我们可以在2.0使用。看起来像问题是与我已经在pom.xml中 提供下面的依赖编码器 –
<依赖性> org.apache.spark 火花core_2.10 2.0.0 org.apache.spark 火花sql_2.10 2.0.0 –
这不是您所拥有版本的正确文档版本。这是2.0.0预览,隐式导入在2.0.0-preview和2.0.0之间更改。看到这里:https://spark.apache.org/docs/2.0.0/sql-programming-guide.html –