Regex for ^ (the caret symbol)?
I am not sure I understand what worked perfectly, since it is my understanding that ^ is only special at the beginning of the regex (to anchor the pattern at the beginning of the target string) or as the first character of a character set (to indicate exclusion of the listed characters). In any other position the caret should behave like an ordinary character. That is, your original pattern should have worked as-is. This is supported by the help page documentation for regex in the paragraph below the definition of [:xdigit:]. I think this is a bug in R.
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mtb954 at gmail.com wrote:
Hi Tsjerk, many thanks...that worked perfectly! Mark Na On Mon, Jan 21, 2013 at 9:36 AM, Tsjerk Wassenaar <tsjerkw at gmail.com> wrote:
Oh, I'm jetlagged. ^ is a control character for 'start of string'. In
the
context of a character set it means negation: [^a-z]. Ciao, Tsjerk On Mon, Jan 21, 2013 at 4:33 PM, Tsjerk Wassenaar
<tsjerkw at gmail.com>wrote:
Hi Mark Na,
Try:
grepl("latitude\\^2",temp)
^ is a control character for negation, so you have to escape it.
Cheers,
Tsjerk
On Mon, Jan 21, 2013 at 4:26 PM, <mtb954 at gmail.com> wrote:
Hello R-helpers, I am trying to search for string that includes the caret symbol,
using
the
following code:
grepl("latitude^2",temp)
And R doesn't like that. It gives me:
temp<-c("latitude^2","latitude and
latitude^2","longitude^2","longitude
and longitude^2")
temp
[1] "latitude^2" "latitude and latitude^2"
"longitude^2"
"longitude and longitude^2"
grepl("latitude^2",temp)
[1] FALSE FALSE FALSE FALSE I think this must a regex problem, but I can't find out to specify
the
caret using regex.
I would appreciate any help you could provide.
Many thanks,
Mark Na
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______________________________________________ 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.
-- Tsjerk A. Wassenaar, Ph.D. post-doctoral researcher Biocomputing Group Department of Biological Sciences 2500 University Drive NW Calgary, AB T2N 1N4 Canada
-- Tsjerk A. Wassenaar, Ph.D. post-doctoral researcher Biocomputing Group Department of Biological Sciences 2500 University Drive NW Calgary, AB T2N 1N4 Canada
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______________________________________________ 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.