Regular expressions: Difference between revisions

=={{header|R}}==

First, define some strings.

<lang R>

pattern <- "string"

text1 <- "this is a matching string"

text2 <- "this does not match"

</lang>

Matching with grep. The indices of the texts containing matches are returned.

<lang R>

grep(pattern, c(text1, text2)) # 1

</lang>

Matching with regexpr. The positions of the starts of the matches are returned, along with the lengths of the matches.

<lang R>

regexpr(pattern, c(text1, text2))

</lang>

[1] 20 -1

attr(,"match.length")

[1] 6 -1

Replacement

<lang R>

gsub(pattern, "pair of socks", c(text1, text2))

</lang>

[1] "this is a matching pair of socks" "this does not match"