自己加入 scala 的 spark api

Question

之前我发过一个关于scala self join的问题。我正在尝试在 Spark 中实现相同但无法转换。这是问题和我的代码。输入数据集...

Proprty_ID, latitude, longitude, Address 123, 33.84, -118.39, null 234, 35.89, -119.48, null 345, 35.34, -119.39, null

输出数据集

Property_ID1, Property_ID2, distance 123,123,0 123,234,0.1 123,345,0.6 234,234,0 234,123,0.1 234,345,0.7 345,345,0 345,123,0.6 345,234,0.7

火花代码：

`import math._

object Haversine {
   val R = 6372.8  //radius in km

   def haversine(lat1:Double, lon1:Double, lat2:Double, lon2:Double)={
      val dLat=(lat2 - lat1).toRadians
      val dLon=(lon2 - lon1).toRadians

      val a = pow(sin(dLat/2),2) + pow(sin(dLon/2),2) * cos(lat1.toRadians) * cos(lat2.toRadians)
      val c = 2 * asin(sqrt(a))
      R * c
   }

   def main(args: Array[String]): Unit = {
      println(haversine(36.12, -86.67, 33.94, -118.40))
  }
}

class SimpleCSVHeader(header:Array[String]) extends Serializable {
  val index = header.zipWithIndex.toMap
  def apply(array:Array[String], key:String):String = array(index(key))
}


val csv = sc.textFile("geo.csv")  // original file
val data = csv.map(line => line.split(",").map(elem => elem.trim)) //lines in rows
val header = new SimpleCSVHeader(data.take(1)(0)) // we build our header with the first line
val rows = data.filter(line => header(line,"latitude") != "latitude") // filter the header out

// val users = rows.map(row => header(row,"user")
// val usersByHits = rows.map(row => header(row,"user") -> header(row,"hits").toInt)

val typed = rows.map{ case Array(id, lat, lon) => (id, lat.toDouble, lon.toDouble)}

`

在此之后，我需要对 typed 进行自连接并通过 Haversine 方法传递它。我从社区获得了如下所示的 Scala 代码，我需要将其转换为 Spark 代码以使用 RDD。以下代码目前适用于列表。

`val combos = for {
    a <- typed
    b <- typed
  } yield (a,b)

combos.map{ case ((id1, lat1, lon1), (id2, lat2, lon2)) 
     => id1 + "," + id2 + "," + haversine(lat1, lon1, lat2, lon2)} foreach println`

有人可以帮忙吗？提前致谢。

Answer 1

你想要的Spark操作是cartesian。您可以在 Spark: produce RDD[(X, X)] of all possible combinations from RDD[X].

了解更多信息

自己加入 scala 的 spark api

self join in spark with scala api

list

scala

apache-spark

rdd

haversine