Reverse list AFTER x Depending vl-position

[hosneyalaa]

Sorry English is not good

Hello all 
If possible, help If he has the following list 

(setq lst-pt '((2.91097 7.9291) (15.2064 6.99916) (12.7764 1.72037) (0.268183 0.311625)))

 

Depending on the location of the item

(reverseLITP lst-pt   2)

((2.91097 7.9291) (15.2064 6.99916) (0.268183 0.311625) (12.7764 1.72037))

 

OR 

(reverseLITP lst-pt   1)

((2.91097 7.9291) (0.268183 0.311625) (12.7764 1.72037) (15.2064 6.99916))

 

 

Thanks, thanks ALL

 

[Tharwat]

Here is one way.

(defun reverse:list (lst pos / lft run new lft out)
  (and (< pos (length lst))
       (setq lft lst
             run -1
       )
       (repeat pos
         (setq new (cons (nth (setq run (1+ run)) lst) new)
               lft (cdr lft)
         )
       )
       (setq out (append (reverse new) (reverse lft)))
  )
  out
)

[dlanorh]

45 minutes ago, hosneyalaa said:

Sorry English is not good

Hello all 
If possible, help If he has the following list 

(setq lst-pt '((2.91097 7.9291) (15.2064 6.99916) (12.7764 1.72037) (0.268183 0.311625)))

 

Depending on the location of the item

(reverseLITP lst-pt   2)

((2.91097 7.9291) (15.2064 6.99916) (0.268183 0.311625) (12.7764 1.72037))

 

OR 

(reverseLITP lst-pt   1)

((2.91097 7.9291) (0.268183 0.311625) (12.7764 1.72037) (15.2064 6.99916))

 

 

Thanks, thanks ALL

 

 

Try this

 

(defun revlstp (lst p / nlst)
  (repeat p (setq nlst (cons (car lst) nlst) lst (cdr lst)))
  (reverse (append lst nlst))
)

 

[hanhphuc]

Nice Tharwat & dlnorh

(defun foo (i l / n k)
  (setq n (length l))
  (cond
    ((not i)(reverse l))
    ((< i n)
      (repeat (1+ i)
        (setq k (cons (car l) k)
              l (cdr l)
        )
      )
       (apply 'append (mapcar 'reverse (list k l)))
    )
    (t nil)
  )
)

 

this reverse (1+ nth)

(setq lst '(1 2 3 4 5 6 7))
(foo nil lst) ;(7 6 5 4 3 2 1)
(foo 0 lst) ;(1 7 6 5 4 3 2)
(foo 3 lst) ;(1 2 3 4 7 6 5)
(foo 6 lst) ;(1 2 3 4 5 6 7)
(foo 7 lst) ; nil

 

 

(defun revnth (n lst)
;hp 25.06.2020
  ((lambda (f n l) (reverse (append (f (- (length lst) n) (reverse lst)) (f n lst))))
    (list '(n l) '(if (> n 0) (cons (nth (1- n) l) (f (1- n) l)))) n l )
  )

 

reverse at nth
(setq lst '( 1 2 3 4 5 6 7 8 9 10 ) )
(revnth 0 lst) ; (10 9 8 7 6 5 4 3 2 1 0 )
(revnth 2 lst) ; (0 1 10 9 8 7 6 5 4 3 2 )
 

 

 

 

Edited June 25, 2020 by hanhphuc
add revnth

[hosneyalaa]

Thanks

@Tharwat and @dlanorh  and  @ hanhphuc

Sorry for my late reply
The lisps were shown  working great and I think beautiful

 

thanks ALL

[pBe]

Another

(defun _relist  (lst n)
      ((lambda (i / l m)
             (while (and (< i n) (setq v (Car lst)))
                   (setq l   (cons v l)
                         i   (1+ i)
                         lst (cdr lst))
                   )
             (append (reverse l) (reverse lst))
             )
            0
            )
      )

 

@ hanhphuc 

You just have to go the other way  than the rest of us don't you..    < n before l st  >

(defun revnth (n lst)...
(defun foo (i l / n k)...

 

 

[hanhphuc]

4 hours ago, pBe said:

 

@ hanhphuc 

You just have to go the other way  than the rest of us don't you..    < n before l st  >

 

 

i didn't notice it, it's a habit putting list after n 

perhaps subconsciousness like

cons

apply

mapcar 

vl-remove 

etc..

 

 

 

[hosneyalaa]

 

On 6/25/2020 at 11:18 PM, pBe said:

Another

(defun _relist  (lst n)
      ((lambda (i / l m)
             (while (and (< i n) (setq v (Car lst)))
                   (setq l   (cons v l)
                         i   (1+ i)
                         lst (cdr lst))
                   )
             (append (reverse l) (reverse lst))
             )
            0
            )
      )

 

@ hanhphuc 

You just have to go the other way  than the rest of us don't you..    < n before l st  >

(defun revnth (n lst)...
(defun foo (i l / n k)...

 

 

 

Thanks @pBe