Created DiceSorensen metric, spec, and command.

5 files changed, 177 insertions, 0 deletions

diff --git a/cli/source/core/scala/org/hashtree/stringmetric/cli/command/diceSorensenMetric.scala b/cli/source/core/scala/org/hashtree/stringmetric/cli/command/diceSorensenMetric.scala
new file mode 100755
index 0000000..1e21a2d
--- /dev/null
+++ b/cli/source/core/scala/org/hashtree/stringmetric/cli/command/diceSorensenMetric.scala
@@ -0,0 +1,58 @@
+package org.hashtree.stringmetric.cli.command
+
+import org.hashtree.stringmetric.{ CaseStringCleaner, StringCleanerDelegate }
+import org.hashtree.stringmetric.cli._
+import org.hashtree.stringmetric.cli.command._
+import org.hashtree.stringmetric.distance.DiceSorensenMetric
+
+/**
+ * The diceSorensenMetric [[org.hashtree.stringmetric.cli.command.Command]]. Compares the similarity of two strings
+ * using the Dice coefficient / Sorensen similarity index.
+ */
+object diceSorensenMetric extends Command {
+	override def main(args: Array[String]): Unit = {
+		val options = OptionMapUtility.toOptionMap(args)
+
+		try {
+			// Help.
+			if (options.contains('h) || options.contains('help)) {
+				help()
+				exit(options)
+			// Execute.
+			} else if (options.contains('dashless) && options('dashless).count(_ == ' ') == 1) {
+				execute(options)
+				exit(options)
+			// Invalid syntax.
+			} else {
+				throw new IllegalArgumentException("Expected valid syntax. See --help.")
+			}
+		} catch {
+			case e => error(e)(options)
+		}
+	}
+
+	override def help(): Unit = {
+		val ls = sys.props("line.separator")
+		val tab = "  "
+
+		println(
+			"Compares the similarity of two strings using the Dice coefficient / Sorensen similarity index." + ls + ls +
+			"Syntax:" + ls +
+			tab + "diceSorensenMetric [Options] string1 string2..." + ls + ls +
+			"Options:" + ls +
+			tab + "-h, --help" + ls +
+			tab + tab + "Outputs description, syntax, and options."
+		)
+	}
+
+	override def execute(options: OptionMap): Unit = {
+		val strings = options('dashless).split(" ")
+
+		println(
+			DiceSorensenMetric.compare(
+				strings(0),
+				strings(1)
+			)(new StringCleanerDelegate with CaseStringCleaner).getOrElse("not comparable").toString
+		)
+	}
+}
\ No newline at end of file
diff --git a/cli/source/test/scala/org/hashtree/stringmetric/cli/command/diceSorensenMetricSpec.scala b/cli/source/test/scala/org/hashtree/stringmetric/cli/command/diceSorensenMetricSpec.scala
new file mode 100755
index 0000000..33ea7dd
--- /dev/null
+++ b/cli/source/test/scala/org/hashtree/stringmetric/cli/command/diceSorensenMetricSpec.scala
@@ -0,0 +1,39 @@
+package org.hashtree.stringmetric.cli.command
+
+import org.hashtree.stringmetric.ScalaTest
+import org.junit.runner.RunWith
+import org.scalatest.junit.JUnitRunner
+
+@RunWith(classOf[JUnitRunner])
+final class diceSorensenMetricSpec extends ScalaTest {
+	"diceSorensenMetric" should provide {
+		"main method" when passed {
+			"valid dashless arguments" should executes {
+				"print if they are a match" in {
+					val out = new java.io.ByteArrayOutputStream()
+
+					Console.withOut(out)(
+						diceSorensenMetric.main(Array("--unitTest", "--debug", "aBc", "abc"))
+					)
+
+					out.toString should equal ("1.0\n")
+					out.reset()
+
+					Console.withOut(out)(
+						diceSorensenMetric.main(Array("--unitTest", "--debug", "aBc", "xyz"))
+					)
+
+					out.toString should equal ("0.0\n")
+					out.reset()
+				}
+			}
+			"no dashless arguments" should throws {
+				"IllegalArgumentException" in {
+					evaluating {
+						diceSorensenMetric.main(Array("--unitTest", "--debug"))
+					} should produce [IllegalArgumentException]
+				}
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/core/source/core/scala/org/hashtree/stringmetric/distance/DiceSorensenMetric.scala b/core/source/core/scala/org/hashtree/stringmetric/distance/DiceSorensenMetric.scala
new file mode 100755
index 0000000..efec67c
--- /dev/null
+++ b/core/source/core/scala/org/hashtree/stringmetric/distance/DiceSorensenMetric.scala
@@ -0,0 +1,44 @@
+package org.hashtree.stringmetric.distance
+
+import org.hashtree.stringmetric.{ CompareTuple, MatchTuple, StringCleaner, StringCleanerDelegate, StringMetric }
+import scala.annotation.tailrec
+
+/** An implementation of the Dice, and Sorensen, [[org.hashtree.stringmetric.StringMetric]]. */
+object DiceSorensenMetric extends StringMetric {
+	override def compare(charArray1: Array[Char], charArray2: Array[Char])(implicit stringCleaner: StringCleaner): Option[Float] = {
+		val ca1 = stringCleaner.clean(charArray1)
+		val ca2 = stringCleaner.clean(charArray2)
+
+		if (ca1.length == 0 || ca2.length == 0) None
+		else {
+			val b = bigrams(ca1, ca2)
+			val ms = scoreMatches(b)
+
+			Some((2f * ms) / (b._1.length + b._2.length))
+		}
+	}
+
+	override def compare(string1: String, string2: String)(implicit stringCleaner: StringCleaner): Option[Float] = {
+		if (string1.length > 0 && string1.length == string2.length && string1 == string2) Some(1f)
+		else
+			compare(
+				stringCleaner.clean(string1.toCharArray),
+				stringCleaner.clean(string2.toCharArray)
+			)(new StringCleanerDelegate)
+	}
+
+	private[this] def bigrams(ct: CompareTuple[Char]): MatchTuple[String] = {
+		@tailrec
+		def set(ca: Array[Char], sa: Array[String]): Array[String] = {
+			if (ca.length <= 1) sa
+			else
+				set(ca.tail, sa :+ "" + ca.head + ca.tail.head)
+		}
+
+		(set(ct._1, Array.empty[String]), set(ct._2, Array.empty[String]))
+	}
+
+	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/distance/DiceSorensenMetricSpec.scala b/core/source/test/scala/org/hashtree/stringmetric/distance/DiceSorensenMetricSpec.scala
new file mode 100755
index 0000000..d07673b
--- /dev/null
+++ b/core/source/test/scala/org/hashtree/stringmetric/distance/DiceSorensenMetricSpec.scala
@@ -0,0 +1,35 @@
+package org.hashtree.stringmetric.distance
+
+import org.hashtree.stringmetric.ScalaTest
+import org.junit.runner.RunWith
+import org.scalatest.junit.JUnitRunner
+
+@RunWith(classOf[JUnitRunner])
+final class DiceSorensenMetricSpec extends ScalaTest {
+	"DiceSorensenMetric" should provide {
+		"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)
+				}
+			}
+			"equal arguments" should returns {
+				"1" in {
+					DiceSorensenMetric.compare("abc", "abc").get should be (1.0f)
+				}
+			}
+			"unequal arguments" should returns {
+				"0" in {
+					DiceSorensenMetric.compare("abc", "xyz").get should be (0.0f)
+				}
+			}
+			"valid arguments" should returns {
+				"Float indicating distance" in {
+					DiceSorensenMetric.compare("night", "nacht").get should be (0.25f)
+				}
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/readme.md b/readme.md
index 56174bf..0840cb5 100755
--- a/readme.md
+++ b/readme.md
@@ -1,6 +1,7 @@
 #stringmetric
 A collection of string metrics implemented in Scala. Includes a light-weight core API and CLI for each string metric. The following string metrics are currently supported:
 
+* Dice / Sorensen
 * Hamming
 * Jaro
 * Jaro-Winkler