(defun distogram (d0 &key 
		  header
		  (lwidth 5) (decimals 2) (rwidth 5)
		  (shrink 1)  (str t))
  (let ((d (as-dist d0))) 
    (unless (dist-sorted d)
      (dist-sort d))
    (let ((sum   (dist-sum  d))
	  (bars  (dist-bars d))
	  (min   (dist-min  d))
	  (max   (dist-max  d))
	  (n     (dist-n    d))
	  (fuzz  (dist-fuzz d))
	  (percentSum 0)
	  (fmt   
	   (format nil " ~~~a,~af * ~~~ad = ~~3d% ~~a " 
		   lwidth decimals rwidth)))
      (if header
	  (format t "~a~%" header))
      (dolist (bar bars t)
	(let* ((key     (car bar))
	       (value   (cdr bar))
	       (percent (floor (* 100 (/ value n))))
	       (stars   (round (/ value shrink)))
	       (halfp   (< percentSum 50)))
	  (incf percentSum percent)
	  (format str fmt (+ key (/ fuzz 2)) 
		          value 
		          percent
	  	          (if halfp "<" ">"))
	  (format str "~a~%" (nchars stars "*")))))))
    
(defun demo-distogram ()
  (let ((log (make-dist :fuzz 2)))
    (reset-seed)
    (dotimes (i 1000)
      (dist-add (sqrt (my-random-int 100)) log))
    (with-output-to-string (s)
      (distogram log :shrink 10 :str s))
    ))

(deftest test-distogram ()
  (check
    (samep (demo-distogram)
  "  1.00 *    12 =   1% < *
     3.00 *    68 =   6% < *******
     5.00 *   163 =  16% < ****************
     7.00 *   222 =  22% < **********************
     9.00 *   327 =  32% < *********************************
    11.00 *   208 =  20% > *********************")))