(defun furthest (tbl row rows)
  (let ((max -1) out)
    (dov (one rows (values out max))
      (let ((d (dist tbl row one)))
	(when (> d max)
	  (setf max d
		out one))))))

(defun dist (tbl v1 v2) 
  (let ((sum 0) (n *zip*) inc)
    (do-some2 (num1 num2 v1 v2 (table-nums tbl))    
      (incf sum (expt (- num1 num2) 2))
      (incf n))
    (do-some2 (sym1 sym2 v1 v2 (table-syms tbl))
      (incf sum (if (eq sym1 sym2) 0 1))
      (incf n))
    (/ (sqrt sum) (sqrt n))))

;;;;;;;
(deftest !dist1 ()
  (test 20706 
	(length (!distances "data/autos.lisp"))))

(deftest !dist2 ()
  (test "one:
    #(? ALFA-ROMERO GAS STD TWO HATCHBACK RWD FRONT 
      0.23032072 0.4492536 0.43333325 0.38333353 0.5178433 
      OHCV SIX 0.34339622 MPFI 0.10000007 0.6666667 0.125 
      0.44166666 0.3469388 0.16666667 0.2631579 0.28255796 1)
    two: 
    #(0.15183246 VOLKSWAGEN DIESEL TURBO FOUR SEDAN FWD FRONT 
      0.31195346 0.45671627 0.43333325 0.6583335 0.3223429 
      OHC FOUR 0.13584906 IDI 0.33571428 0.6333334 1.0 
      0.083333336 0.14285715 0.6666667 0.68421054 0.108658955 2)"
	(!dist2-prim)))

(defun !dist2-prim ()
  (with-output-to-string (str)
    (let* ((tbl (data "data/autos.lisp"))
	   (one (svref (table-rows tbl) 1)))
      (format str "one:~% ~a~%two: ~%~a" (row-cells one)
	      (row-cells (furthest  tbl one (table-rows tbl)))))))
  
(deftest !dist3 ()
  (test '((0.0 2 3) (0.57735026 1 3) (0.57735026 1 2) 
	  (0.8164966 3 4) (0.8164966 2 4) (1.0 1 4))
	(!distances "data/weather0.lisp")))

(deftest !dist4 ()
  (test '((0.16217704 2 3) (0.7111274 2 4) (0.7111274 1 2) 
	  (0.8164966 3 4) (0.8164966 1 4) (0.8164966 1 3))
	(!distances "data/weather1.lisp")))

(deftest !dist5 ()
  (let* ((tbl (data "data/weather1.lisp"))
	 (one (svref (table-rows tbl) 0)))
    (test "one: #(SUNNY 1.0 HIGH FALSE NO)
           two: #(SUNNY 0.0 WET TRUE YES)"
	  (with-output-to-string (s)
	    (format s "one: ~a~%two: ~a"
		    (row-cells one)
		    (row-cells 
		     (furthest tbl one (table-rows tbl))))))))

(defun !distances (f)
  (let* (tmp 
	 (tbl (data f))
	 (all (dovs (x n1 (table-rows tbl) tmp)
		(dovs (y n2 (table-rows tbl))
		  (if (< n1 n2)
		      (push (list (dist tbl x y) x y) tmp))))))
    (mapcar #'(lambda(row)
		(list (first row) 
		      (row-id (second row))
		      (row-id (third row))))
	    (sort all #'< :key #'car))))