(def OUT [])
(def N 1)
(declare sane-numbers)

(defn breaks1 [x l b4  max-size]
  (when-not (= x b4)
    (when (>= N max-size)
      (def N 0)
      (def OUT (conj OUT x))))
  (cond 
   (not-empty l) (and (def N (inc N)) (breaks1 (first l) (rest l) x  max-size))
   true (if (not (member? x OUT)) (def OUT (conj OUT x)))))

(defn efb1 [x break-at]
  (if (= x '?)
    x
    (if (<= x (first break-at))
      (first break-at)
      (efb1 x (rest break-at)))))

(defn breaks [l max-size]
  (breaks1 (first l) (rest l) 'nil  max-size)
  (let [result OUT]
    (def OUT []) ;reset
    (def N 1) ;reset
   result))

(defn efb
  ([data] (efb data 10))
  ([data nb] ;nb = no. of bins
     (let [numbers  (sane-numbers data)
	   want     (Math/round (/ (count numbers) (* nb 1.0)))
	   break-at (breaks numbers want)
	   new      (map (fn [datum] (efb1 datum break-at)) data)]
       new)))

(defn efb2
  ([data] (efb1 data 10))
  ([data n] 
    (let [dat (Transpose data)]
      (loop [d dat result []]
        (if (empty? d)
          result
          (recur (rest d) 
                 (conj result (efb (first d) n))))))))

(defn sane-numbers [data]
  (sort (filter #(number? %) data)))