From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Emanuel Berg Newsgroups: gmane.emacs.help Subject: Re: How to delete all nil properties from a plist? Date: Thu, 06 Aug 2015 02:30:15 +0200 Message-ID: <87pp31s1go.fsf@nl106-137-147.student.uu.se> References: <87oaiq3buh.fsf@mbork.pl> <87mvya3bij.fsf@mbork.pl> <871tfmv5d5.fsf@kuiper.lan.informatimago.com> <87si81u09e.fsf@kuiper.lan.informatimago.com> <87mvy5nwid.fsf@kuiper.lan.informatimago.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1438821144 24240 80.91.229.3 (6 Aug 2015 00:32:24 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 6 Aug 2015 00:32:24 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Thu Aug 06 02:32:15 2015 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZN96T-00041H-GY for geh-help-gnu-emacs@m.gmane.org; Thu, 06 Aug 2015 02:32:13 +0200 Original-Received: from localhost ([::1]:42875 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZN96S-0002Ra-J4 for geh-help-gnu-emacs@m.gmane.org; Wed, 05 Aug 2015 20:32:12 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:44659) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZN96H-0002RK-1v for help-gnu-emacs@gnu.org; Wed, 05 Aug 2015 20:32:01 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZN96D-0005pC-Nf for help-gnu-emacs@gnu.org; Wed, 05 Aug 2015 20:32:00 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:49006) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZN96D-0005ov-GZ for help-gnu-emacs@gnu.org; Wed, 05 Aug 2015 20:31:57 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ZN96B-0003pB-NO for help-gnu-emacs@gnu.org; Thu, 06 Aug 2015 02:31:55 +0200 Original-Received: from nl106-137-228.student.uu.se ([130.243.137.228]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 06 Aug 2015 02:31:55 +0200 Original-Received: from embe8573 by nl106-137-228.student.uu.se with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 06 Aug 2015 02:31:55 +0200 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Original-Lines: 43 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: nl106-137-228.student.uu.se Mail-Copies-To: never User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) Cancel-Lock: sha1:ixYZ6F3hcZvEwmKE5l40yNvA8TM= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:106277 Archived-At: "Pascal J. Bourguignon" writes: > Also, notice that doing that, or consing onto the > beginning of the list and calling nreverse when > you're done are equivalent time-complexity wise. > There may be some difference re: cache in actual > contemporaneous computers but it can be seen only on > very long lists. This only uses `cons', `cdr', and `nreverse', so it is linear, right? ("linear" only from going thru the input list.) (require 'cl) (defun plist-drop-nil-props (l) (let ((new) (nil-prop) (prop) ) (cl-loop for x in l do (if (setq prop (not prop)) (if x (setq new (cons x new)) (setq nil-prop t)) (if x (if nil-prop (setq nil-prop nil) (setq new (cons x new)) ) (setq new (cdr new) )))) (nreverse new) )) ;; (plist-drop-nil-props '(nil 1 a 1 b 2 c nil d nil e 5 g nil h) ) ;; => (a 1 b 2 e 5 h) So the list so far: linear: butlast, append constant: cons, cdr, nreverse But the OP should probably use yours anyway... :) -- underground experts united http://user.it.uu.se/~embe8573