This topic covers matching string patterns, as well as extracting or replacing them. For details on defining complicated patterns see Regular Expressions.
grep("query", "subject", optional_args)
grepl("query", "subject", optional_args)
gsub("(group1)(group2)", "\\group#", "subject")
Escaped regex symbols (like
\1) are must be escaped a second time (like
\\1), not only in the
pattern argument, but also in the
By default, the pattern for all commands (grep, sub, regexpr) is not Perl Compatible Regular Expression (PCRE) so some things like lookarounds are not supported. However, each function accepts a
perl=TRUE argument to enable them. See the R Regular Expressions topic for details.