From 7fb8db2e74b6c553f3b5591db689a49d54521574 Mon Sep 17 00:00:00 2001
From: John Benediktsson <mrjbq7@gmail.com>
Date: Wed, 26 Sep 2012 08:39:11 -0700
Subject: [PATCH] math.statistics: adding a normalized-histogram word.

---
 basis/math/statistics/statistics-tests.factor | 3 +++
 basis/math/statistics/statistics.factor       | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/basis/math/statistics/statistics-tests.factor b/basis/math/statistics/statistics-tests.factor
index e181295262..ae614ab534 100644
--- a/basis/math/statistics/statistics-tests.factor
+++ b/basis/math/statistics/statistics-tests.factor
@@ -77,6 +77,9 @@ IN: math.statistics.tests
     "aabbcc" histogram
 ] unit-test
 
+{ H{ { 1 1/2 } { 2 1/6 } { 3 1/3 } } }
+[ { 1 1 1 1 1 1 2 2 3 3 3 3 } normalized-histogram ] unit-test
+
 {
     V{ 0 3 6 9 }
     V{ 1 4 7 }
diff --git a/basis/math/statistics/statistics.factor b/basis/math/statistics/statistics.factor
index 12dac7c672..c610e2a645 100644
--- a/basis/math/statistics/statistics.factor
+++ b/basis/math/statistics/statistics.factor
@@ -227,6 +227,9 @@ PRIVATE>
 : sorted-histogram ( seq -- alist )
     histogram sort-values ;
 
+: normalized-histogram ( seq -- alist )
+    [ histogram ] [ length ] bi '[ _ / ] assoc-map ;
+
 : collect-pairs ( seq quot: ( x -- v k ) -- hashtable )
     [ push-at ] sequence>hashtable ; inline