(defun discretizer (column numbins)
  (let ((out '()))
    (reverse
     (dotimes (x numbins out)
       (if (= x (- numbins 1))
              (push (float (+ (num-max column) 1.0)) out)
              (push (float (+ (num-min column)
                              (* (+ x 1)
                                 (/ (- (num-max column) (num-min column)) numbins))))
                    out))))))

(deftest !discr1 (&aux (column (make-num :max 280 :min 10)) (numbins 3))
  (test (discretizer column numbins) '(100 190 280)))