actsasgeek

class NearestNeighborSpec extends Spec with ShouldMatchers {
	describe( "A Nearest Neighbor classifier") {
		val library = List(
			new Instance( List( 3.0, 3.0), Some( "A")),
			new Instance( List( 4.0, 2.0), Some( "A")),
			new Instance( List( 2.0, 2.0), Some( "B"))
		)
		val nearestNeighbor = new NearestNeighbor( library)
		it( "can find the 1st closest example in the library to a query") {
			val query = new Instance( List( 0.0, 0.0))

actsasgeek

class NearestNeighbor( library: List[Instance]) {
	def classify( query: Instance): Instance = {
		val distanceMeasurements = library.map( example => (query.distanceTo( example), example))
		val sortedDistanceMeasurements = distanceMeasurements.sortWith(( e1, e2) => ( e1._1 - e2._1) < 0)
		val nearestExample = sortedDistanceMeasurements.head._2
		query.assignClassLabel( nearestExample.classLabel)
	}
}

actsasgeek

class Instance( val featureValues: List[Double], classLabel: Option[String] = None) {
	def assignClassLabel( assignedClassLabel: Option[String]): Instance = {
		new Instance( featureValues, assignedClassLabel)
	}

	def distanceTo( otherInstance: Instance): Double = {
		euclideanDistance( featureValues, otherInstance.featureValues)
	}
	
	def euclideanDistance( thisVector: List[ Double], thatVector: List[ Double]): Double = {

actsasgeek

class Instance( featureValues: List[Double], classLabel: Option[String] = None) {
	def assignClassLabel( assignedClassLabel: Option[String]): Instance = {
		new Instance( featureValues, assignedClassLabel)
	}
	
	override def toString(): String = {
		"<'"+classLabel.getOrElse( "None")+"' is ["+featureValues.mkString( ", ")+"]>"
	}
}

actsasgeek

class Instance( featureValues: List[Double], var classLabel: String) {
}

class NearestNeighbor( library: List[Instance]) {
	def classify( query: Instance) {
		query.classLabel = "unknown"
	}
}

object NearestNeighbor {