* uniq
@ 2010-12-04 2:41 Tak Ota
2010-12-04 12:08 ` uniq Stephen Berman
0 siblings, 1 reply; 5+ messages in thread
From: Tak Ota @ 2010-12-04 2:41 UTC (permalink / raw
To: emacs-devel
Do we have something equivalent to the next command? I know the name
is bad as it is not same as UNIQ(1). It works better because sorting
is not required.
-Tak
;;
;; uniq
;;
(defun uniq ()
"Omit duplicated lines."
(interactive)
(save-excursion
(goto-char (point-min))
(while (not (= (point) (point-max)))
(let* ((start (point))
(str (format "^%s"
(regexp-quote
(buffer-substring start
(progn (forward-line 1) (point)))))))
(save-excursion
(while (re-search-forward str nil t)
(delete-region (match-beginning 0) (match-end 0))))))))
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: uniq
2010-12-04 2:41 uniq Tak Ota
@ 2010-12-04 12:08 ` Stephen Berman
2010-12-04 14:09 ` uniq Stefan Monnier
0 siblings, 1 reply; 5+ messages in thread
From: Stephen Berman @ 2010-12-04 12:08 UTC (permalink / raw
To: emacs-devel
On Fri, 3 Dec 2010 18:41:12 -0800 Tak Ota <Takaaki.Ota@am.sony.com> wrote:
> Do we have something equivalent to the next command? I know the name
> is bad as it is not same as UNIQ(1). It works better because sorting
> is not required.
>
> -Tak
>
> ;;
> ;; uniq
> ;;
> (defun uniq ()
> "Omit duplicated lines."
> (interactive)
> (save-excursion
> (goto-char (point-min))
> (while (not (= (point) (point-max)))
> (let* ((start (point))
> (str (format "^%s"
> (regexp-quote
> (buffer-substring start
> (progn (forward-line 1) (point)))))))
> (save-excursion
> (while (re-search-forward str nil t)
> (delete-region (match-beginning 0) (match-end 0))))))))
Would it be faster to avoid nested while-loops?
(defun uniq ()
"Omit duplicated lines."
(interactive)
(let (lines)
(save-excursion
(goto-char (point-min))
(while (not (eobp))
(let* ((beg (line-beginning-position))
(end (line-end-position))
(line (buffer-substring beg end)))
(if (member line lines)
(delete-region beg (1+ end))
(push line lines)
(forward-line)))))))
Steve Berman
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: uniq
2010-12-04 12:08 ` uniq Stephen Berman
@ 2010-12-04 14:09 ` Stefan Monnier
2010-12-05 18:54 ` uniq René Kyllingstad
0 siblings, 1 reply; 5+ messages in thread
From: Stefan Monnier @ 2010-12-04 14:09 UTC (permalink / raw
To: Stephen Berman; +Cc: emacs-devel
> Would it be faster to avoid nested while-loops?
Not sure if `member' is faster than `re-search-forward', but if you
replace re-search-forward with just search-forward (which requires
a bit more care since you need to manually check that matches are
anchored at bol and eol) I'm pretty sure that'll be even faster since it
will then use a more efficient search algorithm that gets faster the
longer the line of text you're looking for.
Stefan
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: uniq
2010-12-04 14:09 ` uniq Stefan Monnier
@ 2010-12-05 18:54 ` René Kyllingstad
2010-12-05 19:15 ` uniq Lennart Borgman
0 siblings, 1 reply; 5+ messages in thread
From: René Kyllingstad @ 2010-12-05 18:54 UTC (permalink / raw
To: Stefan Monnier; +Cc: Stephen Berman, emacs-devel
On Sat, Dec 4, 2010 at 3:09 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>> Would it be faster to avoid nested while-loops?
>
> Not sure if `member' is faster than `re-search-forward', but if you
> replace re-search-forward with just search-forward (which requires
> a bit more care since you need to manually check that matches are
> anchored at bol and eol) I'm pretty sure that'll be even faster since it
> will then use a more efficient search algorithm that gets faster the
> longer the line of text you're looking for.
Even better, use a hash table to keep the already seen lines. Maybe
call it delete-duplicate-lines, similar to delete-matching-lines.
-- René
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: uniq
2010-12-05 18:54 ` uniq René Kyllingstad
@ 2010-12-05 19:15 ` Lennart Borgman
0 siblings, 0 replies; 5+ messages in thread
From: Lennart Borgman @ 2010-12-05 19:15 UTC (permalink / raw
To: René Kyllingstad; +Cc: Stephen Berman, Stefan Monnier, emacs-devel
2010/12/5 René Kyllingstad <listmailemacs@kyllingstad.com>:
> On Sat, Dec 4, 2010 at 3:09 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>>> Would it be faster to avoid nested while-loops?
>>
>> Not sure if `member' is faster than `re-search-forward', but if you
>> replace re-search-forward with just search-forward (which requires
>> a bit more care since you need to manually check that matches are
>> anchored at bol and eol) I'm pretty sure that'll be even faster since it
>> will then use a more efficient search algorithm that gets faster the
>> longer the line of text you're looking for.
>
> Even better, use a hash table to keep the already seen lines. Maybe
> call it delete-duplicate-lines, similar to delete-matching-lines.
Or maybe using a schwarzian transform to sort only line numbers and
then from this list just delete duplicates (moving backwards).
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-12-05 19:15 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2010-12-04 2:41 uniq Tak Ota
2010-12-04 12:08 ` uniq Stephen Berman
2010-12-04 14:09 ` uniq Stefan Monnier
2010-12-05 18:54 ` uniq René Kyllingstad
2010-12-05 19:15 ` uniq Lennart Borgman
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