From: Emanuel Berg <embe8573@student.uu.se>
To: help-gnu-emacs@gnu.org
Subject: Re: How to delete all nil properties from a plist?
Date: Thu, 06 Aug 2015 02:30:15 +0200 [thread overview]
Message-ID: <87pp31s1go.fsf@nl106-137-147.student.uu.se> (raw)
In-Reply-To: 87mvy5nwid.fsf@kuiper.lan.informatimago.com
"Pascal J. Bourguignon" <pjb@informatimago.com>
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
next prev parent reply other threads:[~2015-08-06 0:30 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-01 22:03 How to delete all nil properties from a plist? Marcin Borkowski
2015-08-01 22:11 ` Marcin Borkowski
2015-08-02 1:32 ` Emanuel Berg
[not found] ` <mailman.7753.1438479312.904.help-gnu-emacs@gnu.org>
2015-08-02 1:36 ` Pascal J. Bourguignon
2015-08-02 1:50 ` Emanuel Berg
2015-08-02 3:55 ` Rusi
2015-08-02 16:21 ` Pascal J. Bourguignon
[not found] ` <mailman.7754.1438480361.904.help-gnu-emacs@gnu.org>
2015-08-02 16:24 ` Pascal J. Bourguignon
2015-08-05 23:08 ` Emanuel Berg
[not found] ` <mailman.7864.1438816202.904.help-gnu-emacs@gnu.org>
2015-08-05 23:30 ` Pascal J. Bourguignon
2015-08-05 23:49 ` Emanuel Berg
2015-08-06 0:30 ` Emanuel Berg [this message]
2015-08-06 1:05 ` John Mastro
2015-08-06 1:07 ` John Mastro
[not found] ` <mailman.7867.1438818687.904.help-gnu-emacs@gnu.org>
2015-08-06 2:32 ` Pascal J. Bourguignon
2015-08-07 22:21 ` Emanuel Berg
[not found] ` <mailman.7869.1438821124.904.help-gnu-emacs@gnu.org>
2015-08-06 2:40 ` Pascal J. Bourguignon
2015-08-07 22:32 ` Emanuel Berg
[not found] ` <mailman.7963.1438986782.904.help-gnu-emacs@gnu.org>
2015-08-08 3:56 ` Pascal J. Bourguignon
2015-08-09 1:34 ` Emanuel Berg
[not found] ` <mailman.7996.1439084206.904.help-gnu-emacs@gnu.org>
2015-08-09 2:18 ` Pascal J. Bourguignon
2015-08-09 2:28 ` Emanuel Berg
[not found] ` <mailman.7749.1438467076.904.help-gnu-emacs@gnu.org>
2015-08-01 23:46 ` Pascal J. Bourguignon
[not found] <mailman.7748.1438466648.904.help-gnu-emacs@gnu.org>
2015-08-01 23:43 ` Pascal J. Bourguignon
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