How to deal with decimal number in scala

Question

I have a file like this:

1    4.146846
2    3.201141
3    3.016736
4    2.729412

I want to use toDouble but, it's not working as expected :

val rows = textFile.map { line =>  
     val fields = line.split("[^\\d]+") 
     ((fields(0),fields(1).toDouble))     
}

val Num = rows.sortBy(- _._2).map{case (user , num) => num}.collect.mkString("::")

println(Num)

The result print out is 4.0::3.0::3.0::2.0.
What I expect is 4.146846::3.201141::3.016736::2.729412

How do I do this?

Also see http://stackoverflow.com/questions/12643009/regular-expression-for-floating-point-numbers — Odomontois, Apr 23 '15 at 07:20
Well.... the problem is your regex... `"[^\\d]+"` its splitting the line into 3. `fields: Array[String] = Array(1, 4, 146846)`. — sarveshseri, Apr 23 '15 at 07:38

score 4 · Answer 1 · answered Apr 23 '15 at 07:17

4

Your regular expression is stopping at the decimal point in 4.146846.

Try line.split("[^\\d.]+")

answered Apr 23 '15 at 07:17

millhouse

9,817
4
32
40

score 0 · Answer 2 · edited Apr 23 '15 at 13:19

What about splitting the lines by variant number of whitespaces? The regular expression would be like '[\s]+' . This resumes in two parts per line, one digit and one double string.

My whole program looks like:

object Application {
  def parseDouble(s: String) = 
    try { 
      Some(s.toDouble) 
    } catch { 
      case _ => None 
    }

  def main(args: Array[String]): Unit = {
    val linesIt = "1    3.201141\n2    4.146846\n3    3.016736\n4    2.729412".lines
    var doubles: List[Double] = List.empty
    for (singleLine <- linesIt) {
      val oneDouble = parseDouble(singleLine.split("[\\s]+")(1))
      doubles = if (oneDouble != None) 
        oneDouble.get::doubles
      else
        doubles
    }
    val doublesArr = doubles.toArray
    println("before sorting: " + doublesArr.mkString("::"))
    scala.util.Sorting.quickSort(doublesArr)
    println("after sorting: " + doublesArr.mkString("::"))
  }
}

How to deal with decimal number in scala

2 Answers2