Getting values stored in some specific indices in an array in Scala

Question

I have a String array and let us suppose that I want to get the third , 7th and 11th members from the array and apply some function to these arrays.

I know that I can do it the java way like using if statement but I want to do it the scala way

As an addition to the question, let us suppose that original string has multiple words seperated by comma. I want to apply some mentioned to the third, 7th and 11th members, while rest of the string remains the same.

In other words if the input string was

i1, i2, i3, i4, i5, i6, i7, i8, i9, i10, i11

I want to change it to

i1, i2, f(i3), i4, i5, i6, f(i7), i8, i9, i10, f(i11)

Currently, I am doing it this way

def process(lin1:String):String=
    {

            val line:Array[String]=lin1.split(";")
            var iLength=line.length
            var iTotalColumns=28
            var i=0
            var output:String=""
            for( i<-0 to iLength-1){


                var sTemp=line(i)
                if((i==3)||(i==7)||(i==11))

Shadowlands · Accepted Answer · 2013-10-08 01:33:47Z

1

Try this:

def selective(f: String => String, ixs: Seq[Int])(in: String) =
  in.split(";").zipWithIndex
    .map { 
      case (str, ix) if (ixs.contains(ix)) => f(str)
      case other => other._1
    }

Example call:

scala> val input = "entry1;entry2;entry3;entry4;entry5;entry6;entry7;entry8;entry9;entry10;entry11"
input: String = entry1;entry2;entry3;entry4;entry5;entry6;entry7;entry8;entry9;entry10;entry11

scala> selective(_.toUpperCase, List(2,6,10))(input)
res3: Array[String] = Array(entry1, entry2, ENTRY3, entry4, entry5, entry6, ENTRY7, entry8, entry9, entry10, ENTRY11)

answered Oct 8, 2013 at 1:33

Shadowlands

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9 Comments

MARK Over a year ago

How can I make the selective function return the modified string. I am confused as the map with in the selective function is working on splitted string

Shadowlands Over a year ago

Are you asking how to get the resulting Array[String] back as a single String? If so, just use mkString on the result (eg. ...map{...}.mkString(";")).

MARK Over a year ago

The problem is that I can do mkString but cannot get this value at the point of call. Sorry, I am at beginner level in Scala. I am invoking it like this \n scala.io.Source.fromFile(inputPath+fileName).getLines() map(l=>selective(func,List(1,2,3,26))(l))

Shadowlands Over a year ago

I'm sorry, I'm not sure I understand the problem. If you want selective to return a String instead of an Array[String], tack .mkString(";") on the end of the map within selective. If you want to do it in the map over the lines as per your latest comment, tack it onto the end of the function call: ...(l).mkString(";")). If neither of those cases match your problem, maybe break it out into a separate question?

MARK Over a year ago

Basically I just want to print the line after scala.io.Source.fromFile(inputPath+fileName).getLines() map(l=>selective(func,List(1,2,3,26))(l))

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