remove duplication

Author: sritchie-stripe

algebird-core/src/main/scala/com/twitter/algebird/AveragedValue.scala

@@ -51,7 +51,8 @@ object AveragedGroup extends Group[AveragedValue] {
    * Note that n must be >= k.
    */
   private def stableAverage(n: Long, an: Double, k: Long, ak: Double): Double =
-    (n + k) match {
+    if (n < k) stableAverage(k, ak, n, an)
+    else (n + k) match {
       case 0L => 0.0
       case newCount if (newCount == n) => an
       case newCount =>
@@ -74,27 +75,18 @@ object AveragedGroup extends Group[AveragedValue] {
       var average = 0.0
       iter.foreach {
         case AveragedValue(c, v) =>
-          average =
-            if (count >= c) stableAverage(count, average, c, v)
-            else stableAverage(c, v, count, average)
+          average = stableAverage(count, average, c, v)
           count += c
       }
       Some(AveragedValue(count, average))
     }
 
-  def plus(big: AveragedValue, small: AveragedValue): AveragedValue =
-    if (big.count < small.count) plus(small, big)
-    else {
-      val n = big.count
-      val k = small.count
-      (n + k) match {
-        case 0L => zero
-        case newCount if (newCount == n) => big
-        case newCount =>
-          val newAve = stableAverage(big.count, big.value, small.count, small.value)
-          AveragedValue(newCount, newAve)
-      }
-    }
+  def plus(big: AveragedValue, small: AveragedValue): AveragedValue = {
+    val n = big.count
+    val k = small.count
+    val newAve = stableAverage(n, big.value, k, small.value)
+    AveragedValue(n + k, newAve)
+  }
 }
 
 object Averager extends MonoidAggregator[Double, AveragedValue, Double] {