Tests for nearest_neighbor.scala

nearest_neighbor_spec_1.0.scala

import org.scalatest.Spec
import org.scalatest.matchers.ShouldMatchers

import scala.io.Source;

class InstanceSpec extends Spec with ShouldMatchers {
	describe( "An Instance") {
		val instance = new Instance( List( 0.0, 0.0))
		it( "can calculate the distance between itself and another instance.") {
			val otherInstance = new Instance( List( 3.0, 4.0))
			instance.distanceTo( otherInstance) should be === 25.0
		}
	}
}

class NearestNeighborSpec extends Spec with ShouldMatchers {
	describe( "A Nearest Neighbor classifier") {
		it( "can find the 1st closest example in the library to a query") {
			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)

			val query = new Instance( List( 0.0, 0.0))
			val queryResult = nearestNeighbor.classify( query)
			queryResult.classLabel should be === Some( "B")
		}
	}
	
	it( "can create a library from a text representation of instances as CSVs") {
		val text = """3.0,3.0,A
4.0,2.0,A
2.0,2.0,B"""
		val library = NearestNeighbor.createLibraryFromCSVs( Source.fromString( text).getLines().toList)
		library should be === 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"))
		)
	}
}