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Improve efficiency of motley-batch-lexicase-selection

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This commit is contained in:
Lee Spector 2023-09-03 10:06:42 -04:00
parent 06e9f9445d
commit 1facb741e6
1 changed files with 17 additions and 19 deletions
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36
src/propeller/selection.cljc
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@ -31,26 +31,24 @@
(defn motley-batch-lexicase-selection
"Selects an individual from the population using motley batch lexicase selection.
Cases are combined in random collections of max size (:max-batch-size argmap),
and then the population is passed to lexicase-selection."
Cases are combined in random collections of max size (:max-batch-size argmap)."
[pop argmap]
(let [cases (range (count (:errors (first pop))))
batches (loop [remaining (shuffle cases)
result ()]
(if (empty? remaining)
result
(let [n (inc (rand-int (:max-batch-size argmap)))]
(recur (drop n remaining)
(conj result (take n remaining))))))]
(lexicase-selection (mapv (fn [ind]
(assoc ind
:errors
(mapv (fn [batch]
(reduce + (map #(nth (:errors ind) %)
batch)))
batches)))
pop)
argmap)))
(loop [survivors (map rand-nth (vals (group-by :errors pop)))
cases (shuffle (range (count (:errors (first pop)))))]
(if (or (empty? cases)
(empty? (rest survivors)))
(rand-nth survivors)
(let [batch-size (inc (rand-int (:max-batch-size argmap)))
batch (take batch-size cases)
ind-err-pairs (map (fn [ind]
[ind
(reduce + (map #(nth (:errors ind) %)
batch))])
survivors)
min-err (apply min (map second ind-err-pairs))]
(recur (map first (filter #(= (second %) min-err)
ind-err-pairs))
(drop batch-size cases))))))
(defn epsilon-list
"List of epsilons for each training case based on median absolute deviation of errors."