[R] Regular expression help
pdalgd at gmail.com
Mon Oct 9 17:45:27 CEST 2017
> On 9 Oct 2017, at 17:02 , Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
> I have a file containing "words" like
> where there may be multiple words on a line (separated by spaces). The a, b, and c strings can contain non-space, non-slash characters. I'd like to use gsub() to extract the c strings (which should be empty if there are none).
> A real example is
> "f 147/1315/587 2820/1320/587 3624/1321/587 1852/1322/587"
> which I'd like to transform to
> " 587 587 587 587"
> Another real example is
> "f 1067 28680 24462"
> which should transform to " ".
> I've tried a few different regexprs, but am unable to find a way to say "transform words by deleting everything up to and including the 2nd slash" when there might be zero, one or two slashes. Any suggestions?
I think you might need something like this:
s <- "f 147/1315/587 2820/1320/587 3624/1321/587 1852/1322/587"
l <- strsplit(s, " ")[]
pat <- "[[:alnum:]]*/[[:alnum:]]*/([[:alnum:]]*)"
paste(ifelse(grepl(pat,l),gsub(pat, "\\1", l), ""), collapse=" ")
> Duncan Murdoch
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Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
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