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Implemented epsilon-lexicase selection into propeller

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dndang23 2022-12-28 17:14:54 -05:00
parent 262ddb83a1
commit c5dd970149
2 changed files with 57 additions and 2 deletions
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38
src/propeller/gp.cljc
View File

@ -13,6 +13,38 @@
[propeller.push.instructions.string]
[propeller.push.instructions.vector]))
(defn mean [coll]
(let [sum (apply + coll)
count (count coll)]
(if (pos? count)
(/ sum (float count))
0)))
(defn median [coll]
(let [sorted (sort coll)
cnt (count sorted)
halfway (quot cnt 2.0)]
(if (odd? cnt)
(nth sorted halfway)
(let [bottom (dec halfway)
bottom-val (nth sorted bottom)
top-val (nth sorted halfway)]
(mean [bottom-val top-val])))))
(defn median-absolute-deviation
[coll]
(let [median-val (median coll)]
(median (map #(Math/abs (- % median-val)) coll))))
(defn epsilon-list
[pop]
(let [error-list (map :errors pop)
length (count (:errors (first pop)))]
(loop [epsilons [] i 0]
(if (= i length)
epsilons
(recur (conj epsilons (median-absolute-deviation (map #(nth % i) error-list))) (inc i))))))
(defn report
"Reports information each generation."
[pop generation argmap]
@ -50,7 +82,11 @@
(mapper
(partial error-function argmap (:training-data argmap))
population))
best-individual (first evaluated-pop)]
best-individual (first evaluated-pop)
argmap (if (= (:parent-selection argmap) :epsilon-lexicase)
(assoc argmap :epsilons (epsilon-list evaluated-pop))
argmap)]
(prn argmap)
(if (:custom-report argmap)
((:custom-report argmap) evaluated-pop generation argmap)
(report evaluated-pop generation argmap))

21
src/propeller/selection.cljc
View File

@ -21,9 +21,28 @@
survivors)
(rest cases))))))
(defn epsilon-lexicase-selection
"Selects an individual from the population using epsilon-lexicase selection."
[pop argmap]
(let [epsilons (:epsilons argmap)]
(loop [survivors pop
cases (shuffle (range (count (:errors (first pop)))))]
(if (or (empty? cases)
(empty? (rest survivors)))
(rand-nth survivors)
(let [min-err-for-case (apply min (map #(nth % (first cases))
(map :errors survivors)))
epsilon (nth epsilons (first cases))]
(recur (filter #(<= (Math/abs (- (nth (:errors %) (first cases)) min-err-for-case)) epsilon)
survivors)
(rest cases)))))))
(defn select-parent
"Selects a parent from the population using the specified method."
[pop argmap]
(case (:parent-selection argmap)
:tournament (tournament-selection pop argmap)
:lexicase (lexicase-selection pop argmap)))
:lexicase (lexicase-selection pop argmap)
:epsilon-lexicase (epsilon-lexicase-selection pop argmap)))