"Brute force" find farthest points in a 2D graph.

gistfile1.clj

(defn find-distance
  "Pthagorian distance. Functions x and y are just wrappers around a two-item seq."
  [a-coord b-coord]
  (let [xsize (- (x a-coord) (x b-coord))
        ysize (- (y a-coord) (y b-coord))]
    (sqrt (+ (* xsize xsize) (* ysize ysize)))))

(defn find-farthest-point
  "Takes a point 'pt' (a two-item seq of numbers) and a seq of points and returns
  the farthest point away from 'pt' in 'pt-list'"
  [pt pt-list]
  (last (sort (map (fn [coord] [(find-distance pt coord) pt coord]) pt-list))))

(defn find-farthest-points 
  "Returns the the two points farthest from each other in a 2D graph expressed 
  as a seq of two-item seq 'pt-list'"
  [pt-list]
  (first 
    (sort 
      (comparator (fn[[distance-a _ _] [distance-b _ _]] (> distance-a distance-b))) 
                      (map (fn[coord] (find-farthest-point coord pt-list)) pt-list))))