make list

[Mirsh]

Hi Dears,

I appreciate if you help me for making a list ;

In a list contain several cons that It's cons have several with same CAR ; can i merge CDR of these cons together and a " & "  between them ,

like this

( ( 1 . "a" ) ( 23 . "b" ) ( 42 . "c" ) ( 1 . "d" ) ( 23 . "e" ) ( 42 . "f" ) (42 . "g" ) )  ====> CONVERT TO====> ( ( 1 "a" " & " "d" ) ( 23 "b" " & " "e" ) ( 42 "c" " & " "f" " & " "g" ) )

 

 

[Lee Mac]

This type of operation arises quite frequently - here's one way to approach it:

(defun f ( l / a r )
    (foreach x (reverse l)
        (if (setq a (assoc (car x) r))
            (setq r (subst (vl-list* (car x) (cdr x) " & " (cdr a)) a r))
            (setq r (cons  (list (car x) (cdr x)) r))
        )
    )
    r
)

_$ (f '((1 . "a")(23 . "b")(42 . "c")(1 . "d")(23 . "e")(42 . "f")(42 . "g")))
((1 "a" " & " "d") (23 "b" " & " "e") (42 "c" " & " "f" " & " "g"))

 

Edited December 29, 2020 by Lee Mac

[Mirsh]

autoLEEsp's GOAT; thanks aloooot happy to have a reply from you

thanks it works