Data commit

Task/Statistics-Basic/Scala/statistics-basic.scala

@@ -0,0 +1,21 @@
+def mean(a:Array[Double])=a.sum / a.size
+def stddev(a:Array[Double])={
+   val sum = a.fold(0.0)((a, b) => a + math.pow(b,2))
+   math.sqrt((sum/a.size) - math.pow(mean(a),2))
+}
+def hist(a:Array[Double]) = {
+   val grouped=(SortedMap[Double, Array[Double]]() ++ (a groupBy (x => math.rint(x*10)/10)))
+   grouped.map(v => (v._1, v._2.size))
+}
+def printHist(a:Array[Double])=for((g,v) <- hist(a)){
+   println(s"$g: ${"*"*(205*v/a.size)} $v")
+}
+
+for(n <- Seq(100,1000,10000)){
+   val a = Array.fill(n)(Random.nextDouble)
+   println(s"$n numbers")
+   println(s"Mean: ${mean(a)}")
+   println(s"StdDev: ${stddev(a)}")
+   printHist(a)
+   println
+}