Scala: How to convert a Seq[Array[String]] into Seq[Double]?

Question

I need to split up the data in Seq[Array[String]] type into two Seq[Double] type items.

Sample data : ([4.0|1492168815],[11.0|1491916394],[2.0|1491812028]).

I used var action1, timestamp1 = seq.map(t => (t.split("|"))).flatten.asInstanceOf[Seq[Double]] but didn't get the results as expected. Looking out for valuable suggestions.

Answer 1

Assuming your input is in format "[double1|double2]",

scala> Seq("[4.0|1492168815]","[11.0|1491916394]","[2.0|1491812028]")
res72: Seq[String] = List([4.0|1492168815], [11.0|1491916394], [2.0|1491812028])

drop [ and ], then split by \\|, | is a metacharacter in regex.

scala> res72.flatMap {_.dropRight(1).drop(1).split("\\|").toList}.map{_.toDouble}
res74: Seq[Double] = List(4.0, 1.492168815E9, 11.0, 1.491916394E9, 2.0, 1.491812028E9)

Or you can do

scala> val actTime = seq.flatMap(t => t.map(x => { val temp = x.split("\\|"); (temp(0), temp(1))}))
actTime: Seq[(String, String)] = List((4.0,1492168815), (11.0,1491916394), (2.0,1491812028))

And to separate them into two Seq[Double] you can do

scala> val action1 = actTime.map(_._1.toDouble)
action1: Seq[Double] = List(4.0, 11.0, 2.0)

scala> val timestamp1 = actTime.map(_._2.toDouble)
timestamp1: Seq[Double] = List(1.492168815E9, 1.491916394E9, 1.491812028E9)

If there could be non-double data in input, you should use Try for safer Double conversion,

scala> Seq("[4.0|1492168815]","[11.0|1491916394]","[2.0|1491812028]", "[abc|abc]")
res75: Seq[String] = List([4.0|1492168815], [11.0|1491916394], [2.0|1491812028], [abc|abc])

scala> import scala.util.Success
import scala.util.Success

scala> import scala.util.Try
import scala.util.Try

scala> res75.flatMap {_.dropRight(1).drop(1).split("\\|").toList}
            .map{d => Try(d.toDouble)}
            .collect {case Success(x) => x }
res83: Seq[Double] = List(4.0, 1.492168815E9, 11.0, 1.491916394E9, 2.0, 1.491812028E9)