Re: gnus-summary-limit-to-recipient and

[sigurd@12move.de (Karl Pflästerer)]

On  3 Dez 2004, reinersteib+gmane@imap.cc wrote:

> An elisp question related to this: Give two lists of number, `to' and
> `cc'.  What is the best way to get a list of all numbers that are
> present in both lists?
>
> Example:
>
> to -> (173     175     177 178     180 181 182 183 184)
> cc -> (173 174 175 176 177 178 179 180 181 182 183 184)
>
> goal: (173     175     177 178     180 181 182 183 184)
>
> I have done it as follows (the "not-matching"-part), but maybe I was
> missing a more simple solution:
>
>   (let* ((to ...) ; list of numbers
> 	 (cc ...) ; list of numbers
> 	 (articles
> 	  (if not-matching
> 	      ;; We need the numbers that are in both lists:
> 	      (mapcar (lambda (a)
> 			(and (memq a to) a))
> 		      cc)
> 	    (nconc to cc))))
>     ...)

You could simply write:
    (intersection list1 list2) or
    (nintersection list1 list2)

If the order matters you perhaps have to write:
   (nreverse (nintersection list1 list2))

This is code from the CL lib so a `(require 'cl)' is needed.


   KP