From: Oliver Scholz <alkibiades@gmx.de>
Subject: Re: alist and multiple values for one key
Date: Tue, 21 Jan 2003 11:53:10 +0100 [thread overview]
Message-ID: <u4r82g4ox.fsf@ID-87814.user.dfncis.de> (raw)
In-Reply-To: dafb954c.0301200503.2118ecf9@posting.google.com
ncauderan@hotmail.com (Norbert C.) writes:
> Hi,
>
> I would lile to find the "good way" to retrieve multiple values
> for a given key in an alist.
>
> But I didn't find a natural way to do it. For example :
> (setq trees '((pine . cones) (pine . acorns) (oak . acorns) (maple .
> seeds)))
> ==> ((pine . cones) (pine . acorns) (oak . acorns) (maple . seeds))
> (assoc 'pine trees)
> ==> (pine . cones)
>
> What I'd like is something that returns each value associated with
> 'pine.
If I don't want to `(require 'cl)' I use something like this:
(delq nil
(mapcar (lambda (elt)
(if (eq (car elt) 'pine) elt nil))
mtrees))
You see this (delq nil (mapcar ... in Emacs' sources at some places,
too.
Oliver
--
2 Pluviôse an 211 de la Révolution
Liberté, Egalité, Fraternité!
next prev parent reply other threads:[~2003-01-21 10:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-20 13:03 alist and multiple values for one key Norbert C.
2003-01-20 16:03 ` Friedrich Dominicus
2003-01-20 23:53 ` Hannu Koivisto
2003-01-21 6:30 ` Friedrich Dominicus
2003-01-21 6:57 ` Friedrich Dominicus
2003-01-20 16:07 ` Klaus Berndl
2003-01-20 17:18 ` Kai Großjohann
2003-01-20 17:19 ` Kai Großjohann
2003-01-20 23:45 ` Hannu Koivisto
2003-01-21 10:53 ` Oliver Scholz [this message]
2003-01-21 11:04 ` David Kastrup
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