also-slow.cljs

(defn calculate-fitness [reference-image-data individual-image-data]
  "Takes two vectors of ints 0-255, representing the rgba data for our
  reference image and individual-image-data. Returns the sum of squares
  difference between the two, which represents how similar the two images are."
  (let [differences (map - reference-image-data individual-image-data)
        squares (map #(* % %) differences)
        my-ints (int-array squares)
        sum-of-squares (areduce my-ints idx ret 0 (+ ret (aget my-ints idx)))
        maximum-difference (* (count reference-image-data)
                              (* 256 256))]
    (- 1 (/ sum-of-squares maximum-difference))))

slow.cljs

(defn calculate-fitness [reference-image-data individual-image-data]
  "Takes two vectors of ints 0-255, representing the rgba data for our
  reference image and individual-image-data. Returns the sum of squares
  difference between the two, which represents how similar the two images are."
  (let [differences (map - reference-image-data individual-image-data)
        squares (map #(* % %) differences)
        sum-of-squares (reduce + squares)
        maximum-difference (* (count reference-image-data)
                              (* 256 256))]
    (- 1 (/ sum-of-squares maximum-difference))))