(defun discretize (tbl n &key (using #'ewd) (cautions (make-caution)))
  (labels ((col1 (col)
             (if (header-numericp (first col))
                 (funcall using (rest col) n cautions)
                 (rest col))))
    (let* ((headers     (counted-all (table-columns tbl)))
           (egs         (table-egs tbl))
           (data        (cons headers egs))
           (columns     (transpose data))
           (discretized (mapcar #'col1 columns)))
      (table-copy tbl (reverse (transpose discretized))))))
(defun logc (data n &optional (cautions (make-caution)))
  (log-continuous data n cautions))

(defun ewd (data n &optional (cautions (make-caution)))
  (equal-width-discretization data n cautions))

(defun efd (data n &optional (cautions (make-caution)))
  (equal-frequency-discretization data n cautions))

(defun sane-numbers (data &optional (cautions (make-caution)) (sortp t))
  (let (numbers)
    (dolist (datum data (if sortp (sort (copy-list numbers) #'<) numbers))
      (unless (unknownp datum)
        (if (ok (numberp datum) cautions "~a not a number" datum) 
            (push datum numbers))))))

(deftest test-discretize ()
  (labels ((nums (n tbl)
             (mapcar #'(lambda (x) (nth n x)) (table-egs tbl)))) 
    (let ((tmp (with-output-to-string (s)
                 (dotimes (i 10)
                   (format s "~a = ~a~%" i (efd1 i '(4 8 9))))))
          (raw  (weather-numerics))
          (ewd  (discretize (weather-numerics) 3 :using #'ewd))
          (efd  (discretize (weather-numerics) 3 :using #'efd)))
      (check
        (equalp '(1 1 1 1 1 2 2 3 3 4 34 34)
                (sane-numbers '(1  1 3 1 3 2 34 1 1 ? 2 34 4)))
        (samep tmp "
        0 = 4
        1 = 4
        2 = 4
        3 = 4
        4 = 4
        5 = 8
        6 = 8
        7 = 8
        8 = 8
        9 = 9")
        (equalp (breaks '(1 2 3 4 5 6 6 6 6 6 6 6 6
                          6 6 6 6 6 7 8 9 10 11 12) 3)
                '(3 6 7 10 12))
        (equalp '(2 2 2 2 6 6 6 6 9 9 9)
                (equal-frequency-discretization
                 '(1 1 1 2 3 4 5 6 7 8 9) 3 )))
        (equalp (nums 2 ewd)
                '(96.0 75.333336 96.0 75.333336 85.666664 75.333336 96.0 75.333336 75.333336
                      85.666664 96.0 96.0 96.0 85.666664))
        (equalp (nums 2 efd)
                '(96 75 90 75 90 75 96 75 75 90 96 90 90 90)))))