Modification of 1-NN algorithm to handle kNN

nearest_neighbor_v4.scala

class NearestNeighbor( library: List[Instance]) {
    def classify( query: Instance, k: Int = 3): Instance = {
        val distanceMeasurements = library.map( example => (query.distanceTo( example), example))
        val sortedDistanceMeasurements = distanceMeasurements.sortWith(( e1, e2) => ( e1._1 - e2._1) < 0)
        val kNearestExamples = sortedDistanceMeasurements.take( k)
        val groupedExamples = kNearestExamples.groupBy( x => x._2.classLabel).toList
        val sortedClassesByCounts = groupedExamples.map { kv => (kv._1, kv._2.length)}.sortWith( _._2 > _._2)
        val classWithMostVotes = sortedClassesByCounts.head
        
        query.assignClassLabel( classWithMostVotes._1)
    }
}