add get-brain-less-than to get a brain of a specific quality

src/nn/core.clj

@@ -1,3 +1,5 @@
+;;TODO: actually interesting brains, refactor, better children handling
+
 (defmacro r
   []
   '(use 'nn.core :reload)
@@ -33,7 +35,9 @@
 (defn min-key-seq
   "The minimum of a seq by key"
   [k seq]
-  (apply min-key k seq))
+  (if (empty? seq)
+    nil
+    (apply min-key k seq)))
 
 (defn nn
   "Create a \"neural network\" from a brain, an activation function, and a variation function (that takes a number)"
@@ -247,6 +251,12 @@
        (map (partial score-with-evolver evolver))
        min-seq))
 
+(defn best-brain
+  "Get the best brain of an evolver"
+  [evolver]
+  (min-key-seq (partial score-with-evolver evolver)
+               (:brains evolver)))
+
 (defn worst-score
   "Get the best score of an evolver"
   [evolver]
@@ -265,3 +275,13 @@
                     (map (comp str best-score)
                          (take 1000 (evolution (n-multiplier-evolver n)))))
        "]"))
+
+(defn get-brain-less-than
+  "Evolve an evolver until it's best brain's score is less than the given value,
+   then return the best brain"
+  [n evolver]
+  (->> evolver
+       evolution
+       (take-while #(> (best-score %) n))
+       last
+       best-brain))