;;除去坐标相同的点，传入参数 cxb 为xy坐标表
(defun C-check(cxb / n xxx)
   (setq n 0 m 0 xxx '())
   (setq cxb (vl_sort cxb
             (function (lambda (e1 e2)
                         (< (car e1) (car e2)) ) ) ))
  (while (< n (length cxb))

    (setq cx1 (nth n cxb)
          xxx (cons (nth n cxb) xxx)
            n (1+ n)
          cx2 (nth n cxb)

    )(while (= (car cx1)(car cx2))
        (setq n (+ 1 n) m (1+ m)
              cx2 (nth n cxb))
             
  ))(if (> m 0)
  (princ (strcat " 共有坐标的点 " (itoa m) " 个")))
  (reverse xxx)

)

(defun vl_sort (lst fun / k nlst lst2)
  (foreach n lst
    (setq   k T
         lst2 (apply 'append (mapcar '(lambda (x)
            (if (and K ((eval fun) n x)) (progn (setq k nil) (list n x)) (list x))
          ) nlst))
   nlst (if K (append lst2 (list n)) lst2)
    )
  )
)