accumulators: new mean-variance accumulator

1 files changed, 6 insertions, 1 deletions

diff --git a/src/clojure/contrib/accumulators/examples.clj b/src/clojure/contrib/accumulators/examples.clj
index ec3c1a01..f30483cc 100644
--- a/src/clojure/contrib/accumulators/examples.clj
+++ b/src/clojure/contrib/accumulators/examples.clj
@@ -12,7 +12,7 @@
 		empty-vector empty-list empty-queue empty-set empty-map
 		empty-counter empty-counter-with-total
 		empty-sum empty-product empty-maximum empty-minimum
-		empty-min-max empty-string empty-tuple)]))
+		empty-min-max empty-mean-variance empty-string empty-tuple)]))
 
 ; Vector accumulator: combine is concat, add is conj
 (combine [:a :b] [:c :d] [:x :y])
@@ -74,6 +74,11 @@
       m2 (add-items empty-min-max [(/ 1 2)])]
   (combine m1 m2))
 
+; Mean-variance accumulator: sample mean and sample variance
+(let [m1 (add-items empty-mean-variance [2 4])
+      m2 (add-items empty-mean-variance [6])]
+  (combine m1 m2))
+
 ; String accumulator: combine is concatenation
 (combine "a" "b" "c" "def")
 (add "a" (char 44))