2 Examples top

• link | changes

  ;; we have a list of key colours
  ;; We want to find the one closest to a supplied colour
  ;; We're storing rgb values as [r g b]
  ;; use min-key to find colour that minimizes 
  ;; the euclidean distance between the supplied colour 
  ;; and each key colour
  ;; thanks to rhudson, raek and mfex on #clojure
  
  (defn distance-squared [c1 c2]
    "Euclidean distance between two collections considered as coordinates"
    (->> (map - c1 c2) (map #(* % %)) (reduce +)))
  
  (def key-colours
       {[224 41 224] :purple
        [24 180 46] :green
        [12 129 245] :blue
        [254 232 23] :yellow
        [233 233 233] :white
        [245 27 55] :red
        [231 119 41] :orange
        })
  
  (defn rgb-to-key-colour
    "Find colour in colour map closest to the supplied [r g b] triple"
    [rgb-triple colour-map]
    (colour-map
     (apply min-key (partial distance-squared rgb-triple) (keys colour-map))))
  
  user=> (rgb-to-key-colour [255 0 0] key-colours)
  :red
  

  ;; we have a list of key colours ;; We want to find the one closest to a supplied colour ;; We're storing rgb values as [r g b] ;; use min-key to find colour that minimizes ;; the euclidean distance between the supplied colour ;; and each key colour ;; thanks to rhudson, raek and mfex on #clojure (defn distance-squared [c1 c2] "Euclidean distance between two collections considered as coordinates" (->> (map - c1 c2) (map #(* % %)) (reduce +))) (def key-colours {[224 41 224] :purple [24 180 46] :green [12 129 245] :blue [254 232 23] :yellow [233 233 233] :white [245 27 55] :red [231 119 41] :orange }) (defn rgb-to-key-colour "Find colour in colour map closest to the supplied [r g b] triple" [rgb-triple colour-map] (colour-map (apply min-key (partial distance-squared rgb-triple) (keys colour-map)))) user=> (rgb-to-key-colour [255 0 0] key-colours) :red
• link | changes

  ; "min-key"/"max-key" to "min"/"max" like "sort-by" to "sort"
  (min-key #(Math/abs %) -3 1 4)
  ; 1
  
  (apply min-key #(Math/abs %) [-3 1 4])
  ; 1
  

  ; "min-key"/"max-key" to "min"/"max" like "sort-by" to "sort" (min-key #(Math/abs %) -3 1 4) ; 1 (apply min-key #(Math/abs %) [-3 1 4]) ; 1