Changed compare implemention. It is now required to specify the size of the n-gram. Typically, this was 2.

5 files changed, 55 insertions, 33 deletions

diff --git a/cli/source/core/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetric.scala b/cli/source/core/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetric.scala
index 229e989..de0b302 100755
--- a/cli/source/core/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetric.scala
+++ b/cli/source/core/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetric.scala
@@ -19,7 +19,9 @@ object diceSorensenMetric extends Command {
 				help()
 				exit(options)
 			// Execute.
-			} else if (options.contains('dashless) && options('dashless).count(_ == ' ') == 1) {
+			} else if (options.contains('dashless) && options('dashless).count(_ == ' ') == 1 &&
+				options.contains('n) && ParseUtility.parseInt(options('n)).isDefined
+			) {
 				execute(options)
 				exit(options)
 			// Invalid syntax.
@@ -39,18 +41,21 @@ object diceSorensenMetric extends Command {
 			tab + "diceSorensenMetric [Options] string1 string2..." + ls + ls +
 			"Options:" + ls +
 			tab + "-h, --help" + ls +
-			tab + tab + "Outputs description, syntax, and options."
+			tab + tab + "Outputs description, syntax, and options." +
+			tab + "--n" + ls +
+			tab + tab + "The n, traditionally 2."
 		)
 	}
 
 	override def execute(options: OptionMap): Unit = {
 		val strings = options('dashless).split(" ")
+		val n = ParseUtility.parseInt(options('n)).get
 
 		println(
 			DiceSorensenMetric.compare(
 				strings(0),
 				strings(1)
-			)(new StringFilterDelegate with AsciiLetterCaseStringFilter).getOrElse("not comparable").toString
+			)(n)(new StringFilterDelegate with AsciiLetterCaseStringFilter).getOrElse("not comparable").toString
 		)
 	}
 }
\ No newline at end of file
diff --git a/cli/source/test/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetricSpec.scala b/cli/source/test/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetricSpec.scala
index d9e2cb0..1e2c286 100755
--- a/cli/source/test/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetricSpec.scala
+++ b/cli/source/test/scala/org/hashtree/stringmetric/cli/similarity/diceSorensenMetricSpec.scala
@@ -13,14 +13,14 @@ final class diceSorensenMetricSpec extends ScalaTest {
 					val out = new java.io.ByteArrayOutputStream()
 
 					Console.withOut(out)(
-						diceSorensenMetric.main(Array("--unitTest", "--debug", "aBc", "abc"))
+						diceSorensenMetric.main(Array("--unitTest", "--debug", "--n=2", "aBc", "abc"))
 					)
 
 					out.toString should equal ("1.0\n")
 					out.reset()
 
 					Console.withOut(out)(
-						diceSorensenMetric.main(Array("--unitTest", "--debug", "aBc", "xyz"))
+						diceSorensenMetric.main(Array("--unitTest", "--debug", "--n=2", "aBc", "xyz"))
 					)
 
 					out.toString should equal ("0.0\n")
diff --git a/core/source/core/scala/org/hashtree/stringmetric/StringMetric.scala b/core/source/core/scala/org/hashtree/stringmetric/StringMetric.scala
index 9cabb82..078361b 100755
--- a/core/source/core/scala/org/hashtree/stringmetric/StringMetric.scala
+++ b/core/source/core/scala/org/hashtree/stringmetric/StringMetric.scala
@@ -10,11 +10,11 @@ trait StringMetric extends Metric[String] {
 
 /** Convenience object for those extending [[org.hashtree.stringmetric.StringMetric]]. */
 object StringMetric {
-	def compareDiceSorensen(charArray1: Array[Char], charArray2: Array[Char])(implicit stringFilter: StringFilter): Option[Double] =
-		DiceSorensenMetric.compare(charArray1, charArray2)(stringFilter)
+	def compareDiceSorensen(charArray1: Array[Char], charArray2: Array[Char])(n: Int)(implicit stringFilter: StringFilter): Option[Double] =
+		DiceSorensenMetric.compare(charArray1, charArray2)(n)(stringFilter)
 
-	def compareDiceSorensen(string1: String, string2: String)(implicit stringFilter: StringFilter): Option[Double] =
-		DiceSorensenMetric.compare(string1, string2)(stringFilter)
+	def compareDiceSorensen(string1: String, string2: String)(n: Int)(implicit stringFilter: StringFilter): Option[Double] =
+		DiceSorensenMetric.compare(string1, string2)(n)(stringFilter)
 
 	def compareHamming(charArray1: Array[Char], charArray2: Array[Char])(implicit stringFilter: StringFilter): Option[Int] =
 		HammingMetric.compare(charArray1, charArray2)(stringFilter)
diff --git a/core/source/core/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetric.scala b/core/source/core/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetric.scala
index cc13fa3..d77c8e7 100755
--- a/core/source/core/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetric.scala
+++ b/core/source/core/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetric.scala
@@ -1,30 +1,33 @@
 package org.hashtree.stringmetric.similarity
 
-import org.hashtree.stringmetric.{ FilterableStringMetric, MatchTuple, StringFilter, StringMetric, StringFilterDelegate }
+import org.hashtree.stringmetric.{ FilterableConfigurableStringMetric, MatchTuple, StringFilter, StringMetric, StringFilterDelegate }
 
-/** An implementation of the Dice, and Sorensen, [[org.hashtree.stringmetric.StringMetric]]. */
-object DiceSorensenMetric extends StringMetric with FilterableStringMetric {
-	override def compare(charArray1: Array[Char], charArray2: Array[Char])(implicit stringFilter: StringFilter): Option[Double] = {
+/**
+ * An implementation of the Dice, and lesser known Sorensen, [[org.hashtree.stringmetric.StringMetric]]. This
+ * implementation differs in that n-gram size is required. Traditionally, the algorithm uses bigrams.
+ */
+object DiceSorensenMetric extends StringMetric with FilterableConfigurableStringMetric[Int] {
+	override def compare(charArray1: Array[Char], charArray2: Array[Char])(n: Int)(implicit stringFilter: StringFilter): Option[Double] = {
 		val ca1 = stringFilter.filter(charArray1)
 		val ca2 = stringFilter.filter(charArray2)
 
 		if (ca1.length == 0 || ca2.length == 0) None
-		else if (ca1.length < 2 || ca2.length < 2) Some(0d) // Because length is less than that of bigram, it will always be 0.
+		else if (ca1.length < n || ca2.length < n) Some(0d) // Because length is less than n, it will always be 0.
 		else if (ca1.sameElements(ca2)) Some(1d)
 		else {
-			val ca1bg = NGramAlgorithm.compute(ca1)(2).get
-			val ca2bg = NGramAlgorithm.compute(ca2)(2).get
+			val ca1bg = NGramAlgorithm.compute(ca1)(n).get
+			val ca2bg = NGramAlgorithm.compute(ca2)(n).get
 			val ms = scoreMatches((ca1bg.map(_.mkString), ca2bg.map(_.mkString)))
 
 			Some((2d * ms) / (ca1bg.length + ca2bg.length))
 		}
 	}
 
-	override def compare(string1: String, string2: String)(implicit stringFilter: StringFilter): Option[Double] =
+	override def compare(string1: String, string2: String)(n: Int)(implicit stringFilter: StringFilter): Option[Double] =
 		compare(
 			stringFilter.filter(string1.toCharArray),
 			stringFilter.filter(string2.toCharArray)
-		)(new StringFilterDelegate)
+		)(n: Int)(new StringFilterDelegate)
 
 	private[this] def scoreMatches(mt: MatchTuple[String]) = mt._1.intersect(mt._2).length
 }
\ No newline at end of file
diff --git a/core/source/test/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetricSpec.scala b/core/source/test/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetricSpec.scala
index 0e8b3a7..163bab5 100755
--- a/core/source/test/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetricSpec.scala
+++ b/core/source/test/scala/org/hashtree/stringmetric/similarity/DiceSorensenMetricSpec.scala
@@ -10,37 +10,51 @@ final class DiceSorensenMetricSpec extends ScalaTest {
 		"compare method" when passed {
 			"empty arguments" should returns {
 				"None" in {
-					DiceSorensenMetric.compare("", "").isDefined should be (false)
-					DiceSorensenMetric.compare("abc", "").isDefined should be (false)
-					DiceSorensenMetric.compare("", "xyz").isDefined should be (false)
+					DiceSorensenMetric.compare("", "")(1).isDefined should be (false)
+					DiceSorensenMetric.compare("abc", "")(1).isDefined should be (false)
+					DiceSorensenMetric.compare("", "xyz")(1).isDefined should be (false)
 				}
 			}
 			"equal arguments" should returns {
 				"1" in {
-					DiceSorensenMetric.compare("abc", "abc").get should be (1)
+					DiceSorensenMetric.compare("abc", "abc")(1).get should be (1)
+					DiceSorensenMetric.compare("abc", "abc")(2).get should be (1)
+					DiceSorensenMetric.compare("abc", "abc")(3).get should be (1)
 				}
 			}
 			"unequal arguments" should returns {
 				"0" in {
-					DiceSorensenMetric.compare("abc", "xyz").get should be (0)
+					DiceSorensenMetric.compare("abc", "xyz")(1).get should be (0)
+					DiceSorensenMetric.compare("abc", "xyz")(2).get should be (0)
+					DiceSorensenMetric.compare("abc", "xyz")(3).get should be (0)
 				}
 			}
 			"invalid arguments" should returns {
 				"Double indicating distance" in {
-					DiceSorensenMetric.compare("n", "naght").get should be (0)
-					DiceSorensenMetric.compare("night", "n").get should be (0)
+					DiceSorensenMetric.compare("n", "naght")(2).get should be (0)
+					DiceSorensenMetric.compare("night", "n")(2).get should be (0)
+					DiceSorensenMetric.compare("ni", "naght")(3).get should be (0)
+					DiceSorensenMetric.compare("night", "na")(3).get should be (0)
 				}
 			}
 			"valid arguments" should returns {
 				"Double indicating distance" in {
-					DiceSorensenMetric.compare("night", "nacht").get should be (0.25)
-					DiceSorensenMetric.compare("night", "naght").get should be (0.5)
-					DiceSorensenMetric.compare("context", "contact").get should be (0.5)
-					DiceSorensenMetric.compare("contextcontext", "contact").get should be (0.3157894736842105)
-					DiceSorensenMetric.compare("context", "contactcontact").get should be (0.3157894736842105)
-					DiceSorensenMetric.compare("ht", "nacht").get should be (0.4)
-					DiceSorensenMetric.compare("xp", "nacht").get should be (0)
-					DiceSorensenMetric.compare("ht", "hththt").get should be (0.3333333333333333)
+					DiceSorensenMetric.compare("night", "nacht")(1).get should be (0.6)
+					DiceSorensenMetric.compare("night", "naght")(1).get should be (0.8)
+					DiceSorensenMetric.compare("context", "contact")(1).get should be (0.7142857142857143)
+
+					DiceSorensenMetric.compare("night", "nacht")(2).get should be (0.25)
+					DiceSorensenMetric.compare("night", "naght")(2).get should be (0.5)
+					DiceSorensenMetric.compare("context", "contact")(2).get should be (0.5)
+					DiceSorensenMetric.compare("contextcontext", "contact")(2).get should be (0.3157894736842105)
+					DiceSorensenMetric.compare("context", "contactcontact")(2).get should be (0.3157894736842105)
+					DiceSorensenMetric.compare("ht", "nacht")(2).get should be (0.4)
+					DiceSorensenMetric.compare("xp", "nacht")(2).get should be (0)
+					DiceSorensenMetric.compare("ht", "hththt")(2).get should be (0.3333333333333333)
+
+					DiceSorensenMetric.compare("night", "nacht")(3).get should be (0)
+					DiceSorensenMetric.compare("night", "naght")(3).get should be (0.3333333333333333)
+					DiceSorensenMetric.compare("context", "contact")(3).get should be (0.4)
 				}
 			}
 		}