Topic: how to insert new value into list

[RAIN CODE]

Hi guys,

How to write the shortest lisp using mapcar or lambda to insert a value into a list. Say I have 5 scores - (list 10000 9000 8000 7000 6000). And a new high score of 8500 to insert into this list, meaning the result is 10000 9000 8500 8000 7000. Always end with 5 highest score only, notice the last item in the list 6000 is removed from the list. I have written a lisp but its quite long. I wondered if using mapcar or lambda will shorten the lisp ??

Thanks

[Daniel J. Ellis]

I'd probably do a FOREACH loop.

Load each item from the list in turn and compare it to the new value.  If the new value is the highest one replace the new value with the curent one and go to the next term.

dJE

[Stefan]

Code - Auto/Visual Lisp: [Select]

1. (defun ins_item (lst new)
2.   (if lst
3.     (if
4.       (>= new (car lst))
5.        (cons new (reverse (cdr (reverse lst))))
6.        (cons (car lst) (ins_item (cdr lst) new))
7.     )
8.   )
9. )

[kpblc]

Another one:

Code - Auto/Visual Lisp: [Select]

1. (defun test (/ lst value)
2.  
3.   (setq lst   (list 10000 9000 8000 7000 6000)
4.         value 8500
5.         ) ;_ end of setq
6.   (vl-sort (cons value lst) '>)
7.   ) ;_ end of defun

[pBe]

Code - Auto/Visual Lisp: [Select]

1. (defun TopFive  (lst n)
2.       (if (>  n (last lst))
3.             (reverse
4.                   (cdr (vl-sort
5.                              (cons n lst)
6.                              '<)))
7.             lst)
8.       )

(topfive  '(10000 9000 8000 7000 6000) 8500)
(10000 9000 8500 8000 7000)

(topfive  '(10000 9000 8000 7000 6000) 5500)
(10000 9000 8000 7000 6000)

(topfive  '(10000 9000 8000 7000 6000) 11500)
(11500 10000 9000 8000 7000)

[Stefan]

kpblc and pBe

Code: [Select]

(setq lst '(10 8 8 8 6))

[pBe]

Busted   

Code - Auto/Visual Lisp: [Select]

1. (defun TopFive  (lst n / a b)
2.       (repeat (length lst)
3.             (if (>= (setq a (car lst)) n)
4.                   (setq b   (append b (list a))
5.                         lst (cdr lst))
6.                   (setq b (append b (list n))
7.                         n 0)))
8.       b)

[irneb]

If AutoLisp had the same implementation as the common lisp "last" function this could have been written as:

Code - Auto/Visual Lisp: [Select]

1. (reverse (last (vl-sort (cons value lst) '<) 5))

Otherwise something similar could be use from my code here: http://alisp-ext.wikidot.com/autolisp-firstn

E.g.

Code - Auto/Visual Lisp: [Select]

1. (FirstN (vl-sort (cons value lst) '>) 5)

[irneb]

BTW, is the list always only 5 items in length? I.e. you never have a list with more (or less) to begin with? If so your code could be:

Code - Auto/Visual Lisp: [Select]

1. (reverse (cdr (vl-sort (cons value lst) '<)))

This would work for any length list ... keeping it the same length as it was by dropping the smallest value after adding the new value. Basically what pBe did - just ignoring the actual length.

[Faster]

Code - Auto/Visual Lisp: [Select]

1. (setq l '(10000 9000 8000 7000 6000) )
2. (defun insertn (l n)
3.   (if (> (car l) n)
4.     (cons (car l) (insertn (cdr l) n))
5.     (if l
6.       (cons n (reverse (cdr (reverse l))))
7.     ) ;_ if
8.   ) ;_ if
9. ) ;_ defun
10. ;;test
11. (insertn l 7500)
12.  

[Lee Mac]

Iterative version of Stefan's:

Code - Auto/Visual Lisp: [Select]

1. (defun f ( x l / o )
2.     (while (and (setq a (car l)) (< x a))
3.         (setq o (cons a o)
4.               l (cdr l)
5.         )
6.     )
7.     (reverse (append (cdr (reverse (cons x l))) o))
8. )

Code - Auto/Visual Lisp: [Select]

1. _$ (f 8500 '(10000 9000 8000 7000 6000))
2. (10000 9000 8500 8000 7000)

[Stefan]

The 'mapcar way

Code - Auto/Visual Lisp: [Select]

1. (defun ins_item_1 (l n)
2.   (mapcar
3.     '(lambda (x / m)
4.        (if (>= n x) (setq m n n x x m))
5.        x
6.      )
7.     l
8.   )
9. )

[Lee Mac]

Another 

Code - Auto/Visual Lisp: [Select]

1. (defun f ( l n / g h )
2.     (defun g ( a b ) (h a b))
3.     (defun h ( a b ) (if (< n a) a (progn (defun h ( a b ) b) n)))
4.     (mapcar 'g l (cons nil l))
5. )

[RAIN CODE]

wow ! you guys are pretty good. Amazing. All the suggestions here are shorter than my lisp.

to irneb - yes.. the list is always 5 in length. Well maybe I will make it 10 (top ten hi score).

I will post the game here once it finished.  The most used function in the game is the one suggested by CAB about 2 weeks ago, to replace old list with new value. It took me an hour or two to understand that function with mapcar and lambda.  Its so amazingly short, its like Einstein's famous equation E=mc sq 

Thanks guys - you all are the greatest.

[ElpanovEvgeniy]

another 2

Code - Auto/Visual Lisp: [Select]

1. (defun f (l n) (mapcar '(lambda (a b) (nth a (cons n l))) (vl-sort-i (cons n l) '>) l))