From 91067caf66442cad082ee4ae446a33452eea9e2c Mon Sep 17 00:00:00 2001
From: Eric Schulte <schulte.eric@gmail.com>
Date: Wed, 17 Nov 2010 11:38:34 -0700
Subject: [PATCH] initial implementation of self organizing maps    - running
 is working    - learning is working    - training is working

---
 src/neural_net/self_organizing_maps.clj | 47 +++++++++++++++++++++++++++++++--
 1 file changed, 45 insertions(+), 2 deletions(-)

diff --git a/src/neural_net/self_organizing_maps.clj b/src/neural_net/self_organizing_maps.clj
index 71936b1..7b72f6b 100644
--- a/src/neural_net/self_organizing_maps.clj
+++ b/src/neural_net/self_organizing_maps.clj
@@ -1,4 +1,47 @@
 (ns neural-net.self-organizing-maps     ; Kohonen maps
-  (:use neural-net.core))
+  (:use neural-net.core)
+  (:use clojure.set))
 
-;; TODO -- implement
+(defn self-organizing-map:run
+  "Return a map of the dot product of each neurons weight against x" [this x]
+  (reduce (fn [a [k v]] (cons [k (reduce + (map * x (v :weights)))] a))
+          [] (get (this :map) :vertices)))
+
+(defn self-organizing-map:learn
+  "Return a map of learning spread through the map." [this x y d]
+  (let [verts (map first (reverse (sort-by second y)))]
+    (loop [ns [(first verts)] rem (set (rest verts)) dist 0 out {}]
+      (if (empty? ns)
+        out
+        (let [m (filter (partial contains? rem) (mapcat (partial neighbors (this :map)) ns))]
+          (recur m (difference rem (set m)) (inc dist)
+                 (reduce (fn [a n] (assoc a n ((this :update) this dist n x)))
+                         out ns)))))))
+
+(defn self-organizing-map:train [this delta]
+  (assoc this
+    :map (neural-net.core.Graph.
+          (reduce (fn [a [k d]] (assoc a k (map + d ((get a k) :weights))))
+                  (get (this :map) :vertices) delta)
+          (get (this :map) :edges))))
+
+(comment                                ; train a self organizing map
+  (let [som {:phi self-organizing-map:run
+             :learn self-organizing-map:learn
+             :train self-organizing-map:train
+             :eta 1
+             :update (fn [this dist n x]
+                       (map (fn [x] (* (/ x (inc dist)) (this :eta)))
+                            (map -
+                                 x (((get (this :map) :vertices) n) :weights))))
+             :map (neural-net.core.Graph.
+                   {:a {:weights [ 1  0]}
+                    :b {:weights [ 0  1]}
+                    :c {:weights [-1  0]}
+                    :d {:weights [ 0 -1]}}
+                   [[:a :b] [:b :c] [:c :d]])}]
+    (first (train som [0.8 0.2] nil nil)))
+  ;; =>
+  ;; {:d (0.2 0.3),  :c (0.6 0.06666666666666667),
+  ;;  :b (0.4 -0.4), :a (-0.19999999999999996 0.2)}  
+  )
-- 
2.11.4.GIT