### Regular Expressions (Introduction to Statistical Computing)

Lecture
21: Regular expressions. Why we need ways of describing patterns of
strings, and not just specific strings. The syntax and semantics of regular
expressions: constants, concatenation, alternation, repetition.
Back-references and capture groups. Splitting on regular
expressions. `grep` and
`grepl` for finding matches. `regexpr` and `gregexpr` for
finding matches, `regmatches` for extracting the matching substrings.
`regexec` for capture groups. Examples of multi-stage processing with
regular expressions. Examples of substitutions with `regmatches`,
`sub` and `gsub`. Things you cannot do with regular expressions.

Examples: Lincoln's
2nd inaugural
address; baking
brownies with Ms. Alice
B. Tolkas; extracting
earthquake information from data files.

*Readings*: Matloff, chapter 11; R Cookbook, chapter 7;
Spector, chapter 7. *Optional readings*: Bradnam and Korf, sections
4.26--4.28, 5.3, 6.1

Introduction to Statistical Computing

Posted at November 06, 2013 10:30 | permanent link