regex - Multiple regexpr in one string in R

Question

So I have a really long string and I want to work with multiple matches. I can only seem to get the first position of the first match using regexpr. How can I get multiple positions (more matches) back within the same string?

I am looking for a specific string in html source code. The titel of an auction (which is between html tags). It prooves kind of difficult to find:

So far I use this:

locationstart <- gregexpr("<span class="location-name">", URL)[[1]]+28
locationend <- regexpr("<", substring(URL, locationstart[1], locationend[1] + 100))
substring(URL, locationstart[1], locationstart[1] + locationend - 2)

That is, I look for a part that comes before a title, then I capture that place, from there on look for a "<" indicating that the title ended. I'm open for more specific suggestions.

Answer 1

Using gregexpr allows for multiple matches.

> x <- c("only one match", "match1 and match2", "none here")
> m <- gregexpr("match[0-9]*", x)
> m
[[1]]
[1] 10
attr(,"match.length")
[1] 5
attr(,"useBytes")
[1] TRUE

[[2]]
[1]  1 12
attr(,"match.length")
[1] 6 6
attr(,"useBytes")
[1] TRUE

[[3]]
[1] -1
attr(,"match.length")
[1] -1
attr(,"useBytes")
[1] TRUE

and if you're looking to extract the match you can use regmatches to do that for you.

> regmatches(x, m)
[[1]]
[1] "match"

[[2]]
[1] "match1" "match2"

[[3]]
character(0)