Topic: ----<<Challenge>>----atom to nested list

[Jeremy Dunn]

I am searching for a function that will take an atom and substitute it for the atoms in a supplied list or just return the atom if the supplied list is an atom itself.
Some examples:

(atom2lst 3 5) -> 3
(atom2lst 2 '(3 5)) -> (2 2)
(atom2lst  2 ((1 2)((3 4) 5))) -> ((2 2)((2 2) 2))

[d2010]

He say her son like chocolate.
Ask her if Son likes choco.

Code: [Select]

Command: (defun q2 (a1 / $rr 2) (setq $rr 2)) ?> Q2
Command: (mapcar 'q2 '(1 2 3 4)) ?> (2 2 2 2)
Command: (mapcar 'q2 '((1 2)((3 4) 5))) ?> (2 2)
Command: (mapcar 'q2 '((1 2)((3 4) 5))) ?>(2 2)
Command: (subst  *  2 '(1 2 3)) ?>(1 #<SUBR @06ebc588 *> 3)


[Lee Mac]

No dotted pairs:

Code - Auto/Visual Lisp: [Select]

1. (defun atom2lst ( a b )
2.     (if (listp b) (mapcar '(lambda ( x ) (atom2lst a x)) b) a)
3. )

[Lee Mac]

To cater for dotted pairs:

Code - Auto/Visual Lisp: [Select]

1. (defun atom2lst ( a b )
2.     (cond
3.         (   (null b) nil)
4.         (   (atom b) a)
5.         (   (cons (atom2lst a (car b)) (atom2lst a (cdr b))))
6.     )
7. )

Code - Auto/Visual Lisp: [Select]

1. _$ (atom2lst 2 '(3 . 5))
2. (2 . 2)
3. _$ (atom2lst 2 '(3 5))
4. (2 2)

[MP]

If Lee’s posts had a love child (untested - coded blind on iPad - not yet able to sit at a computer) ... should be able to process regular lists as well as dotted pairs:

Code: [Select]

(defun atl (a x)
    (cond
        ((null x) nil)
        ((atom x) a)
        ((vl-list-length x) (mapcar '(lambda (l) (atl a l)) x))
        ((cons (atl a (car x)) (atl a (cdr x))))
    )
)

[Lee Mac]

Nice one MP, though my second function will already process standard lists too 

Hope you're on the mend!

[MP]

Well that’s what I get for coding blind. I’m

Getting a little better each day - just like all of us.

Thanks Lee.