Add scala demos (gstamatelat#26)

demo-scala/build.gradle

@@ -0,0 +1,18 @@
+apply plugin: 'scala'
+
+repositories {
+    jcenter()
+}
+
+sourceSets {
+    main {
+        scala {
+            srcDirs = ['src']
+        }
+    }
+}
+
+dependencies {
+    compile rootProject,
+            'org.scala-lang:scala-library:2.12.6'
+}

demo-scala/src/SelectRandomFromRange.scala

@@ -0,0 +1,16 @@
+import java.util.Random
+
+import gr.james.sampling.WatermanSampling
+
+import scala.collection.JavaConverters._
+
+/**
+  * Select 10 numbers at random in the range [1,100] using [[WatermanSampling]]. Each number has a 10% probability of
+  * appearing in the sample.
+  */
+object SelectRandomFromRange extends App {
+  val rs = new WatermanSampling[Int](10, new Random)
+  rs.feed((1 to 100).iterator.asJava)
+  val sample = rs.sample
+  println(sample)
+}

demo-scala/src/SelectRandomFromStreamX.scala

@@ -0,0 +1,12 @@
+import java.util.{Random, Scanner}
+
+import gr.james.sampling.VitterXSampling
+
+/**
+  * Select 5 random tokens from an input stream using [[VitterXSampling]].
+  */
+object SelectRandomFromStreamX extends App {
+  val rs = new VitterXSampling[String](5, new Random)
+  rs.feed(new Scanner(System.in))
+  System.out.println(rs.sample)
+}

demo-scala/src/SelectRandomFromStreamZ.scala

@@ -0,0 +1,12 @@
+import java.util.{Random, Scanner}
+
+import gr.james.sampling.VitterZSampling
+
+/**
+  * Select 5 random tokens from an input stream using [[VitterZSampling]].
+  */
+object SelectRandomFromStreamZ extends App {
+  val rs = new VitterZSampling[String](5, new Random)
+  rs.feed(new Scanner(System.in))
+  System.out.println(rs.sample)
+}

demo-scala/src/SelectWeightedFromVocabulary.scala

@@ -0,0 +1,17 @@
+import java.util.Random
+
+import gr.james.sampling.EfraimidisSampling
+
+/**
+  * Select 2 terms from a vocabulary using [[EfraimidisSampling]], based on their weight.
+  */
+object SelectWeightedFromVocabulary extends App {
+  val rs = new EfraimidisSampling[String](2, new Random)
+  rs.feed("collection", 1)
+  rs.feed("algorithms", 2)
+  rs.feed("java", 2)
+  rs.feed("random", 3)
+  rs.feed("sampling", 4)
+  rs.feed("reservoir", 5)
+  System.out.println(rs.sample)
+}

demo-scala/src/UnweightedStream.scala

@@ -0,0 +1,25 @@
+import java.util.Random
+
+import gr.james.sampling.{RandomSampling, WatermanSampling}
+
+import scala.collection.JavaConverters._
+
+/**
+  * Unweighted random sampling using functional constructs.
+  */
+object UnweightedStream extends App {
+  val sample = (0 until 20)
+    .foldLeft(construct[Int](5, new Random()))(foldOperation)
+    .sample().asScala.toList
+
+  def construct[T](sample: Int, random: Random): RandomSampling[T] =
+    new WatermanSampling[T](sample, random)
+
+  def foldOperation[T] =
+    (rs: RandomSampling[T], i: T) => {
+      rs.feed(i)
+      rs
+    }
+
+  println(sample)
+}

demo-scala/src/WeightedStream.scala

@@ -0,0 +1,33 @@
+import java.util.Random
+
+import gr.james.sampling.{ChaoSampling, WeightedRandomSampling}
+
+import scala.collection.JavaConverters._
+
+/**
+  * Weighted random sampling using functional constructs.
+  */
+object WeightedStream extends App {
+  val map = Map(
+    "collection" -> 1.0,
+    "algorithms" -> 2.0,
+    "java" -> 2.0,
+    "random" -> 3.0,
+    "sampling" -> 4.0,
+    "reservoir" -> 5.0
+  )
+  val sample = map
+    .foldLeft(construct[String](2, new Random()))(foldOperation)
+    .sample().asScala.toList
+
+  def construct[T](sample: Int, random: Random): WeightedRandomSampling[T] =
+    new ChaoSampling[T](sample, random)
+
+  def foldOperation[T] =
+    (wrs: WeightedRandomSampling[T], i: (T, Double)) => {
+      wrs.feed(i._1, i._2)
+      wrs
+    }
+
+  println(sample)
+}

demo/build.gradle

@@ -1,5 +1,4 @@
 apply plugin: 'java'
-apply plugin: 'findbugs'
 
 sourceCompatibility = 1.8
 
@@ -15,10 +14,6 @@ sourceSets {
     }
 }
 
-findbugs {
-    effort = "max"
-}
-
 dependencies {
     compile rootProject
 }

demo/src/SelectRandomFromStreamX.java

@@ -1,7 +1,6 @@
 import gr.james.sampling.RandomSampling;
 import gr.james.sampling.VitterXSampling;
 
-import java.nio.charset.Charset;
 import java.util.Random;
 import java.util.Scanner;
 
@@ -11,7 +10,7 @@
 public final class SelectRandomFromStreamX {
     public static void main(String[] args) {
         RandomSampling<String> rs = new VitterXSampling<>(5, new Random());
-        rs.feed(new Scanner(System.in, Charset.defaultCharset().name()));
+        rs.feed(new Scanner(System.in));
         System.out.println(rs.sample());
     }
 }

demo/src/SelectRandomFromStreamZ.java

@@ -1,7 +1,6 @@
 import gr.james.sampling.RandomSampling;
 import gr.james.sampling.VitterZSampling;
 
-import java.nio.charset.Charset;
 import java.util.Random;
 import java.util.Scanner;
 
@@ -11,7 +10,7 @@
 public final class SelectRandomFromStreamZ {
     public static void main(String[] args) {
         RandomSampling<String> rs = new VitterZSampling<>(5, new Random());
-        rs.feed(new Scanner(System.in, Charset.defaultCharset().name()));
+        rs.feed(new Scanner(System.in));
         System.out.println(rs.sample());
     }
 }

settings.gradle

@@ -1,2 +1,2 @@
 rootProject.name = 'random-sampling'
-include 'demo'
+include 'demo', 'demo-scala'