如何在Spark中对嵌套的Dataframe进行flatmap

Question

我有嵌套字符串,如下所示.我想平面映射它们以在Spark中生成唯一的行

我的数据框有

A,B,"x,y,z",D

我想将其转换为生成输出

A,B,x,D
A,B,y,D
A,B,z,D

我怎样才能做到这一点.

基本上我如何做平面地图并在Dataframe中应用任何功能

谢谢

Answer 1

Spark 2.0+

Dataset.flatMap:

val ds = df.as[(String, String, String, String)]
ds.flatMap { 
  case (x1, x2, x3, x4) => x3.split(",").map((x1, x2, _, x4))
}.toDF

Spark 1.3+.

用途split和explode 功能:

val df = Seq(("A", "B", "x,y,z", "D")).toDF("x1", "x2", "x3", "x4")
df.withColumn("x3", explode(split($"x3", ",")))

Spark 1.x

DataFrame.explode (在Spark 2.x中弃用)

df.explode($"x3")(_.getAs[String](0).split(",").map(Tuple1(_)))