Hadoop practice, a small converter for matrix.

covertMatrixJob.scala

/*
  @daunnc, stackoverflow: http://stackoverflow.com/questions/20020967/transforming-matrix-format-scalding-solved
  
  converts
    1 2 3 
    3 4 5
    6 7 8 
    
  to

    1 1 1
    1 2 2
    1 3 3
    2 1 3
    2 2 4
    2 3 5
    3 1 5
    3 2 6
    3 3 7 
  
  */
  
import com.twitter.scalding._
//import com.twitter.scalding.FunctionImplicits._ to use implicit -- after comments

class convertMatrixJob(args: Args) extends Job(args) {
  var prev: Long = 0
  var pos: Long = 1
  
  val zeroInt = 0
  val zeroDouble = 0.0

  TextLine(args("input"))
    .flatMap('line -> 'number)  { line : String => line.split("\\s+") }
    .mapTo(('offset, 'line, 'number) -> ('row, 'col, 'val)) { res : (Long, String, String) => //(offset: Long, line: String, number: String) 
      val (offset, line, number) = res // del line if using implicits
      pos = if(prev == (offset + 1)) pos + 1 else 1
      prev = offset + 1
      (offset + 1, pos, number) }
    .filter('row, 'col, 'v) { line : (Long, String, String) =>
      val (row, col, v) = line
      (v != zeroInt.toString) && (v != zeroDouble.toString) 
    }
    .write(Tsv(args("output")))
}