From: Oleh Krehel <ohwoeowho@gmail.com>
To: Thierry Volpiatto <thierry.volpiatto@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: What to do for faster `remove-duplicates'?
Date: Wed, 06 May 2015 19:54:49 +0200 [thread overview]
Message-ID: <87r3qtzj4m.fsf@gmail.com> (raw)
In-Reply-To: <87bnhxeh4j.fsf@gmail.com> (Thierry Volpiatto's message of "Wed, 06 May 2015 19:43:40 +0200")
Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
>> Looks good, please install.
>
> Not so good as now it is no more destructive for a seq > 100.
Should I make it destructive, like this?
(defun delete-dups (list)
"Destructively remove `equal' duplicates from LIST.
Store the result in LIST and return it. LIST must be a proper list.
Of several `equal' occurrences of an element in LIST, the first
one is kept."
(if (> (length list) 100)
(let ((hash (make-hash-table :test #'equal))
res)
(dolist (elt list)
(unless (gethash elt hash)
(puthash elt elt hash)
(push elt res)))
(setcdr list (cdr (nreverse res))))
(let ((tail list))
(while tail
(setcdr tail (delete (car tail) (cdr tail)))
(setq tail (cdr tail)))))
list)
Oleh
next prev parent reply other threads:[~2015-05-06 17:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-06 7:33 What to do for faster `remove-duplicates'? Oleh Krehel
2015-05-06 12:59 ` Stefan Monnier
2015-05-06 13:30 ` Oleh Krehel
2015-05-06 13:50 ` Stefan Monnier
2015-05-06 13:51 ` Oleh Krehel
2015-05-06 17:43 ` Thierry Volpiatto
2015-05-06 17:54 ` Oleh Krehel [this message]
2015-05-06 18:31 ` Artur Malabarba
2015-05-06 18:33 ` Artur Malabarba
2015-05-06 18:41 ` Oleh Krehel
2015-05-06 19:24 ` Artur Malabarba
2015-05-06 19:32 ` Oleh Krehel
2015-05-06 21:22 ` Artur Malabarba
2015-05-06 18:48 ` Thierry Volpiatto
2015-05-06 20:54 ` Stefan Monnier
2015-05-06 20:54 ` Stefan Monnier
2015-05-06 21:18 ` Artur Malabarba
2015-05-06 14:04 ` Artur Malabarba
2015-05-06 14:13 ` Oleh Krehel
2015-05-06 14:49 ` Artur Malabarba
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