Re: Detecting repeated phrase in a string
| От | Shaozhong SHI |
|---|---|
| Тема | Re: Detecting repeated phrase in a string |
| Дата | |
| Msg-id | CA+i5JwaEwK=ktV-H-xS2dHgGfWL0RPRDVhcghJ5rQM45DqLY-g@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Detecting repeated phrase in a string ("Peter J. Holzer" <hjp-pgsql@hjp.at>) |
| Ответы |
Re: Detecting repeated phrase in a string
|
| Список | pgsql-general |
Hi, Peter,
How to define word boundary as either by using
^ , space, or $
So that the following can be done
fox fox is a repeat
foxfox is not a repeat but just one word.
Regards,
David
On Thu, 9 Dec 2021 at 13:35, Peter J. Holzer <hjp-pgsql@hjp.at> wrote:
On 2021-12-09 12:38:15 +0000, Shaozhong SHI wrote:
> Does anyone know how to detect repeated phrase in a string?
Use regular expressions with backreferences:
bayes=> select regexp_match('foo wikiwiki bar', '(.+)\1');
╔══════════════╗
║ regexp_match ║
╟──────────────╢
║ {o} ║
╚══════════════╝
(1 row)
"o" is repeated in "foo".
bayes=> select regexp_match('fo wikiwiki bar', '(.+)\1');
╔══════════════╗
║ regexp_match ║
╟──────────────╢
║ {wiki} ║
╚══════════════╝
(1 row)
"wiki" is repeated in "wikiwiki".
bayes=> select regexp_match('fo wikiwi bar', '(.+)\1');
╔══════════════╗
║ regexp_match ║
╟──────────────╢
║ (∅) ║
╚══════════════╝
(1 row)
nothing is repeated.
Adjust the expression within parentheses if you want to match somethig
more specific than any sequence of one or more characters.
hp
--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp@hjp.at | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"
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