evovle.clj

;; single-generation cycle: select -> crossover -> mutate
(defn next-generation [population]
  ""
  (->> (sort-by calculate-fitness population)
        vec
        roulette-select
        pair
       (map cycle-crossover)
       (reduce into)
       (map (fn [x] (if (should-mutate?)
                        (mutate x)
                        x)))))

;; full evolution cycle (many generations)
(defn evolve [max-gen gen-size draw-chan]
  "performs the generation cycle for
   [max-gen] number of generations"
  (loop [population (create-population gen-size num-cities)
         cur-gen    0]
    (if (< cur-gen max-gen)
      (let [ngen     (next-generation population)
            gen-num  (inc cur-gen)
            best-fit (calculate-fitness (first (sort-by calculate-fitness ngen)))
            avg-fit  (float (/ (reduce + (map calculate-fitness ngen)) (count ngen)))]
        (do
          (go
           (>! draw-chan (mapv calculate-fitness (sort-by calculate-fitness ngen))))
          (recur ngen gen-num)))
      population)))