R help - Jan 2013 - Regex for ^ (the caret symbol)?

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

	[[alternative HTML version deleted]]

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@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
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@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

	[[alternative HTML version deleted]]

On Mon, 21 Jan 2013, mtb954 at gmail.com wrote:
> I am trying to search for string that includes the caret symbol, using the
> following code:
> grepl("latitude^2",temp)
   Many regex implementations require us to escape a metacharacter such as
'^' by preceeding it with a backslash. This indicates the next character
is
a literal and not, in this case, the beginning of the line. Try \^ in your
statement.

Rich