From eed44cfc065fca2f71c969172b27764402c81186 Mon Sep 17 00:00:00 2001
From: Lee Spector <lspector@hampshire.edu>
Date: Sat, 20 Jun 2020 00:05:09 -0400
Subject: [PATCH] Reduce code duplication; additions before/after each gene;
 deletion runs on result of addition; tweak default parameters

---
 src/propeller/core.clj      |  4 +--
 src/propeller/gp.clj        | 52 ++++++++++++++-----------------------
 src/propeller/variation.clj | 29 +++++++++------------
 3 files changed, 33 insertions(+), 52 deletions(-)

diff --git a/src/propeller/core.clj b/src/propeller/core.clj
index 5cbbd1e..30fbeb9 100644
--- a/src/propeller/core.clj
+++ b/src/propeller/core.clj
@@ -13,8 +13,8 @@
                            :max-initial-plushy-size 50
                            :step-limit              100
                            :parent-selection        :lexicase
-                           :tournament-size         20
-                           :UMADRate                0.2
+                           :tournament-size         5
+                           :UMADRate                0.1
                            :variation               {:UMAD 0.5 :crossover 0.5}
                            :elitism                 false}
                           (apply hash-map
diff --git a/src/propeller/gp.clj b/src/propeller/gp.clj
index 0088377..37dd33b 100644
--- a/src/propeller/gp.clj
+++ b/src/propeller/gp.clj
@@ -24,37 +24,23 @@
            max-initial-plushy-size]
     :as   argmap}]
   (println "Starting GP with args:" argmap)
-  (if
-    (:elitism argmap)
-    (loop [generation 0
-           population (repeatedly
-                        population-size
-                        #(hash-map :plushy
-                                   (make-random-plushy instructions
-                                                       max-initial-plushy-size)))]
-      (let [evaluated-pop (sort-by :total-error
-                                   (map (partial error-function argmap)
-                                        population))]
-        (report evaluated-pop generation)
-        (cond
-          (zero? (:total-error (first evaluated-pop))) (println "SUCCESS")
-          (>= generation max-generations) nil
-          :else (recur (inc generation)
-                       (conj (repeatedly (- population-size 1)
-                                         #(new-individual evaluated-pop argmap)) (first evaluated-pop))))))
-    (loop [generation 0
-           population (repeatedly
-                        population-size
-                        #(hash-map :plushy
-                                   (make-random-plushy instructions
-                                                       max-initial-plushy-size)))]
-      (let [evaluated-pop (sort-by :total-error
-                                   (map (partial error-function argmap)
-                                        population))]
-        (report evaluated-pop generation)
-        (cond
-          (zero? (:total-error (first evaluated-pop))) (println "SUCCESS")
-          (>= generation max-generations) nil
-          :else (recur (inc generation)
+  (loop [generation 0
+         population (repeatedly
+                      population-size
+                      #(hash-map :plushy
+                                 (make-random-plushy instructions
+                                                     max-initial-plushy-size)))]
+    (let [evaluated-pop (sort-by :total-error
+                                 (map (partial error-function argmap)
+                                      population))]
+      (report evaluated-pop generation)
+      (cond
+        (zero? (:total-error (first evaluated-pop))) (println "SUCCESS")
+        (>= generation max-generations) nil
+        :else (recur (inc generation)
+                     (if (:elitism argmap)
+                       (conj (repeatedly (dec population-size)
+                                         #(new-individual evaluated-pop argmap))
+                             (first evaluated-pop))
                        (repeatedly population-size
-                                   #(new-individual evaluated-pop argmap))))))))
\ No newline at end of file
+                                   #(new-individual evaluated-pop argmap))))))))
diff --git a/src/propeller/variation.clj b/src/propeller/variation.clj
index 6c613a1..af6972e 100644
--- a/src/propeller/variation.clj
+++ b/src/propeller/variation.clj
@@ -16,22 +16,18 @@
                  longer))))
 
 (defn uniform-addition
-  "Randomly adds new instructions before every instruction (and at the end of
-  the plushy) with some probability."
+  "Returns plushy with new instructions possibly added before or after each existing instruction."
   [plushy instructions UMADRate]
-  (let [rand-code (repeatedly (inc (count plushy))
-                              (fn []
-                                (if (< (rand) UMADRate)
-                                  (rand-nth instructions)
-                                  :mutation-padding)))]
-    (remove #(= % :mutation-padding)
-            (interleave (conj plushy :mutation-padding)
-                        rand-code))))
+  (apply concat
+         (map #(if (< (rand) UMADRate)
+                 (shuffle [% (rand-nth instructions)])
+                 [%])
+              plushy)))
 
 (defn uniform-deletion
   "Randomly deletes instructions from plushy at some rate."
   [plushy UMADRate]
-  (remove (fn [x] (< (rand)
+  (remove (fn [_] (< (rand)
                      (/ 1 (+ 1 (/ 1 UMADRate)))))
           plushy))
 
@@ -46,10 +42,9 @@
        (crossover (:plushy (select-parent pop argmap))
                   (:plushy (select-parent pop argmap)))
        (< prob (+ (:crossover (:variation argmap))
-                  (/ (:UMAD (:variation argmap)) 2)))
-       (do (uniform-addition (:plushy (select-parent pop argmap))
-                             (:instructions argmap)
-                             (:UMADRate argmap))
-           (uniform-deletion (:plushy (select-parent pop argmap))
-                             (:UMADRate argmap)))
+                  (:UMAD (:variation argmap)) 2))
+       (uniform-deletion (uniform-addition (:plushy (select-parent pop argmap))
+                                           (:instructions argmap)
+                                           (:UMADRate argmap))
+                         (:UMADRate argmap))
        :else (:plushy (select-parent pop argmap))))})
\ No newline at end of file