Regular expressions are a form of pattern that are often be used in data detectors to recognise entities in text or during data wrangling to validate data. Regular expression are a very simple formal grammar with limited expressivity, for example they cannot match brackets. There are slightly different flavours but typically include matching fixed text, grouping with brackets, alternatives '(acd|def)', characters in sets '[abc789]', repetitions 'a*' and optional items 'a?' `and wildcards '.'. For example, '(a(bc|de)f*)' matches 'abc', 'ade', 'abcf', 'adef', abcff', adeff', ... and so on with and more 'f's at the end.
Used on Chap. 10: page 201; Chap. 14: pages 327, 328, 329, 340; Chap. 17: pages 406, 417
Links:
developer.mozilla.org: This Mozilla guide describes {{JavaScript}} regular expressions in detail.- regexr.com: RegExr -- one of a number of online regular expression checkers
- regex101.com: Regular expressions 101 -- another online checker, with quick reference, and allowng dfferent 'flavours' of regexp to be selected.
- Wikipedia: Regular expression -- includes theoretical background