[求助]：怎样去除表中相同的元素最有效率？？

gewanjia · 发表于 2005-12-4 16:19:27

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大虾们：
我现在编写一个画单线图程序，遇到点问题大家帮助解决！！

list表中有许多相同的元素，我只想一样保留一个，我怎样才能最有效率去掉呢？？
（请原谅我有点c语言的后遗症）SIZE[/SIZE]

Underway · 发表于 2005-12-4 16:43:37

;; by CAB
(defun unique (lst / result)
(while (setq itm (car lst))
(setq lst (vl-remove itm lst)
result (cons itm result)
)
)
)
;; by MP
(defun unique ( lst / result )
(foreach item lst
(if (null (member item result))
(setq result (cons item result))
)
)
(reverse result)
)
;; by MP
(defun unique2 ( lst / result )
(foreach item lst
(if (null (assoc (car item) result))
(setq result (cons item result))
)
)
(reverse result)
)
;; by Fatty
(defun remove-first (lst /)
(while
(member (caar lst) (mapcar 'car (cdr lst)))
(setq lst (vl-remove-if
(function (lambda (x)
(eq (car x) (caar lst))
)
)
lst
)
)
)
lst
)

;;  by CAB 
(defun unique (lst / result) 
    (while (setq itm (car lst)) 
      (setq lst (vl-remove itm lst) 
            result (cons itm result) 
      ) 
    ) 
  ) 
 
;; by MP 
(defun unique ( lst / result ) 
    (foreach item lst 
        (if (null (member item result)) 
            (setq result (cons item result)) 
        ) 
    ) 
    (reverse result) 
) 
 
;; by MP 
(defun unique2 ( lst / result ) 
    (foreach item lst 
        (if (null (assoc (car item) result)) 
            (setq result (cons item result)) 
        ) 
    ) 
    (reverse result) 
) 
 
;; by Fatty 
(defun remove-first (lst /) 
  (while 
    (member (caar lst) (mapcar 'car (cdr lst))) 
     (setq lst (vl-remove-if 
                (function (lambda (x) 
                             (eq (car x) (caar lst)) 
                           ) 
                ) 
                lst 
               ) 
     ) 
  ) 
  lst 
)

snoopychen · 发表于 2005-12-4 17:53:41

http://www.theswamp.org/forum/index.php?topic=7891.0
应该就是underway兄提到的吧

taner · 发表于 2005-12-4 18:59:59

對於表處理,再慢也不會慢到哪裏去!
作爲不同的編程思路和方法,倒是可以借鑒的.

xyp1964 · 发表于 2005-12-4 19:17:37

[FONT=courier new](defun LstDelSame (lst / x nl)
(foreach x lst
(if (not (member x nl))
(setq nl (cons x nl))
)
)
(reverse nl)
)[/FONT]

taner · 发表于 2005-12-4 19:51:25

最初由 xyp1964 发布
[B]
[FONT=courier new](defun LstDelSame (lst / x nl)

 (foreach x lst

(if (not (member x nl))

 (setq nl (cons x nl))

)

 )

 (reverse nl)

)[/FONT]
[FONT=courier new](defun LstDelSame (lst / x nl) (foreach x lst (if (not (member x nl)) (setq nl (cons x nl)) ) ) (reverse nl) )[/FONT]
[/B]

版主,有個疑問:

程序中nl沒有設初值,一般來講.其初值應該爲nil.但是如果在別的程序中有全局變量nl,是否有時候造成結果不對?

Underway · 发表于 2005-12-4 20:56:32

(defun LstDelSame (lst / x nl)
 (princ "\n Nl = ") (princ nl) ; <=== Check here, and you'll got the answer
 (foreach x lst
(if (not (member x nl))
 (setq nl (cons x nl))
)
 )
 (reverse nl)
)

(defun LstDelSame (lst / x)
(princ "\n Nl = ") (princ nl) ; <=== Check here, and you'll got the answer
(foreach x lst
(if (not (member x nl))
(setq nl (cons x nl))
)
)
(reverse nl)
)

taner · 发表于 2005-12-4 21:12:37

最初由 Underway 发布
[B](defun LstDelSame (lst / x nl)
 (princ "\n Nl = ") (princ nl) ; < ==== Check here, and you'll got the answer
 (foreach x lst
(if (not (member x nl))
 (setq nl (cons x nl))
)
... [/B]

谢谢解惑!只要在本函数里将变量设为局部变量就行!

将XYP版主的函数改一下.以前老搞不清FOREACH,MAPCAR,LAMBDA的用法.通过上面几个例了,终于豁然!
[PHP](defun LstDelSame (lst / x nl)
  (mapcar
'(lambda (x)
   (if (not (member x nl))
   (setq nl (cons x nl))
   )
   )
lst
  )
  (reverse nl)
)[/PHP]

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[求助] [求助]：怎样去除表中相同的元素最有效率？？

马上注册，结交更多好友，享用更多功能，让你轻松玩转社区。

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