Reading multiple integers from line in text file - scala

Question

I am using Scala and reading input from the console. I am able to regurgitate the strings that make up each line, but if my input has the following format, how can I access each integer within each line?
2 2
1 2 2
2 1 1
Currently I just regurgitate the input back to the console using
object Main {
def main(args: Array[String]): Unit = {
for (ln <- io.Source.stdin.getLines) println(ln)
//how can I access each individual number within each line?
}
}
And I need to compile this project like so:
$ scalac main.scala
$ scala Main <input01.txt
2 2
1 2 2
2 1 1

Answer 1

A reasonable algorithm would be:
for each line, split it into words
parse each word into an Int
An implementation of that algorithm:
io.Source.stdin.getLines // for each line...
.flatMap(
_.split("""\s+""") // split it into words
.map(_.toInt) // parse each word into an Int
)
The result of this expression will be an Iterator[Int]; if you want a Seq, you can call toSeq on that Iterator (if there's a reasonable chance there will be more than 7 or so integers, it's probably worth calling toVector instead). It will blow up with a NumberFormatException if there's a word which isn't an integer. You can handle this a few different ways... if you want to ignore words that aren't integers, you can:
import scala.util.Try
io.Source.stdin.getLines
.flatMap(
_.split("""\s+""")
.flatMap(Try(_.toInt).toOption)
)

Answer 2

The following will give you a flat list of numbers.
val integers = (
for {
line <- io.Source.stdin.getLines
number <- line.split("""\s+""").map(_.toInt)
} yield number
)
As you can read here, some care must be taken when parsing the numbers.