regular expression help to extract specific strings from text
strapply in gsubfn can extract matches based on content which seems to be what you want: library(gsubfn) f <- function(...) sapply(list(...), paste, collapse = ", ") DF <- data.frame(x, Source = strapply(x, "^(\\w+):", c, simplify = f), Mentions = strapply(x, "@(\\w+)", c, simplify = f), HashTags = strapply(x, "#(\\w+)", c, simplify = f)) DF[DF == ""] <- NA
On Wed, Mar 31, 2010 at 9:20 AM, Tony B <tony.breyal at googlemail.com> wrote:
Dear all, Lets say I have the following:
x <- c("Eve: Going to try something new today...", "Adam: Hey @Eve, how are you finding R? #rstats", "Eve: @Adam, It's awesome, so much better at statistics that #Excel ever was! @Cain & @Able disagree though :(", "Adam: @Eve I'm sure they'll sort it out :)", "blahblah")
x
[1] "Eve: Going to try something new
today..."
[2] "Adam: Hey @Eve, how are you finding R?
#rstats"
[3] "Eve: @Adam, It's awesome, so much better at statistics that
\n#Excel ever was! @Cain & @Able disagree though :("
[4] "Adam: @Eve I'm sure they'll sort it
out :)"
[5] "blahblah"
I would like to come up with a data frame which looks like this
(pulling out the usernames and #tags):
data.frame(Msg = x, Source = c("Eve", "Adam", "Eve", "Adam", NA), Mentions = c(NA, "Eve", "Adam, Cain, Able", "Eve", NA), HashTags = c(NA, "rstats", "Excel", NA, NA))
The best I can do so far is:
source <- lapply(x, function (x) {
? tmp <- strsplit(x, ":", fixed = TRUE)
? if(length(tmp[[1]]) < 2) {
? ? tmp <- c(NA, tmp)
? }
? return(tmp[[1]][1])
?} )
source <- unlist(source)
[1] "Eve" ?"Adam" "Eve" ?"Adam" NA
I can't work out how to extract the usernames starting with '@' or the
#tags. I can identify them using gsub and replace them, but I don't
know how to just extract those terms only, e.g. sort of the opposite
of the following
gsub("@([A-Za-z0-9_]+)", "@[...]", x)
[1] "Eve: Going to try something new today..."
[2] "Adam: Hey @[...], how are you finding R? #rstats"
[3] "Eve: @[...], It's awesome, so much better at statistics that
#Excel ever was! @[...] & @[...] disagree though :("
[4] "Adam: @[...] I'm sure they'll sort it out :)"
[5] "blahblah"
and
gsub("#([A-Za-z0-9_]+)", "#[...]", x)
[1] "Eve: Going to try something new today..."
[2] "Adam: Hey @Eve, how are you finding R? #[...]"
[3] "Eve: @Adam, It's awesome, so much better at statistics that
#[...] ever was! @Cain & @Able disagree though :("
[4] "Adam: @Eve I'm sure they'll sort it out :)"
[5] "blahblah"
I hope that makes sense, and thank you kindly in advance for your
time.
Tony Breyal
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.