Scala - convert Array[String] to Array[Double]

You probably want to use map along with toDouble:

values.map(x => x.toDouble)

Or more concisely:

values.map(_.toDouble)

And for the fallback for non-double strings, you might consider using the Try monad (in scala.util):

values.map(x => Try(x.toDouble).getOrElse(1.0))

If you know what each line will look like, you could also do pattern matching:

values map { 
    case Array(a, b, c) => Array(a.toDouble, b.toDouble, 1.0)
}

You mean to convert all strings to double with a fallback to 1.0 for all inconvertible strings? That would be:

val x = Array(
  Array("1.0", "2.0", "item1"),
  Array("5", "8.9", "item2"))

x.map( _.map { y =>
  try {
    y.toDouble
  } catch {
    case _: NumberFormatException => 1.0
  }
})

Expanding on @DaunnC's comment, you can use the Try utility to do this and pattern match on the result so you can avoid calling get or wrapping your result in an Option:

import scala.util.{Try, Success, Failure}

def main = {
  val maybeDoubles = Array("5", "1.0", "8.5", "10.0", "item1", "item2")

  val convertDoubles = maybeDoubles.map { x =>
    Try(x.toDouble)
  }

  val convertedArray = convertDoubles.map {
    _ match {
      case Success(res) => res
      case Failure(f) => 1.0
   }
  }

  convertedArray
}

This allows you to pattern match on the result of Try, which is always either a Success or Failure, without having to call get or otherwise wrap your results.

Here is some more information on Try courtesy of Mauricio Linhares: https://mauricio.github.io/2014/02/17/scala-either-try-and-the-m-word.html