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
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_ | Peter J. Holzer | Story must make more sense than reality.
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| | | h...@hjp.at | -- Charles Stross, "Creative writing
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