compute distance in km between two postal codes

dist.scala

// using build.sbt: libraryDependencies += "org.apache.spark" %% "spark-core" % sparkVersion % "provided"
// using Ammonite:  import $ivy.`org.apache.sis.core:sis-referencing:0.7`, org.apache.sis.distance.DistanceUtils

case class Coordinates(lat: Double, lon: Double)

def readCoordinates(file: String): Map[String, Coordinates] = {
  def parseLine(line: String): (String, Coordinates) = {
    val c = line.split("\t")
    (c(0) + "-" + c(1), Coordinates(c(9).toDouble, c(10).toDouble))
  }
  // there are some duplicated postal codes. let's take one at random.
  // scala.io.Source.fromFile(filename).getLines.map(f).toList.groupBy(_._1).filter(_._2.size > 1).foreach(println)
  scala.io.Source.fromFile(coordinatesFile).getLines.map(parseLine).toMap
}

def distanceInKm(c1: Coordinates, c2: Coordinates): Double =
  DistanceUtils.getHaversineDistance(c1.lat, c1.lon, c2.lat, c2.lon)

def distanceInKm(postalCode1: String, postalCode2: String): Double =
  distanceInKm(coordinates(postalCode1), coordinates(postalCode2))

// unzip from: http://download.geonames.org/export/zip/allCountries.zip
val coordinates: Map[String, Coordinates] = readCoordinates("./allCountries.txt")
println(coordinates.size) // 612928
coordinates.take(3).foreach(println)
/*
(PT-2950-316,Coordinates(38.569,-8.9013))
(US-57006,Coordinates(44.3056,-96.7914))
(PL-85-455,Coordinates(53.15,18.0))
*/

println(distanceInKm("CH-1200", "CH-1004"))   // Geneva - Lausanne: 50.37 Km
println(distanceInKm("ES-08001", "CH-1004"))  // Barcelona - Lausanne: 673.56 Km

val queryFile = "./query.txt"
scala.io.Source.fromFile(queryFile).getLines.foreach { line =>
  val Array(postalCode1, postalCode2) = line.split("\t")
  println(postalCode1 + "\t" + postalCode2 + "\t" + distanceInKm(postalCode1, postalCode2))
}

/*
FILE query.txt
CH-1200	CH-1004
ES-08001	CH-1004
...

FILE output:
CH-1200	CH-1004	50.37020530697646
ES-08001	CH-1004	673.566602548844
...
*/