[R] extracting text contained in brackets ("[ ... ]") from a character string?

[jim holtman]

here is one way using 'sub':

> x <- c("testdata[3]", "testdata[-4]", "testdata[-4g]")
> sub(".*\\[(.*)\\].*", "\\1", x, perl=TRUE)
[1] "3"   "-4"  "-4g"
> x.func <- function(x){ sub(".*\\[(.*)\\].*", "\\1", x, perl=TRUE)}
> x.func(x)
[1] "3"   "-4"  "-4g"
>


On 5/13/07, new ruser <newruser at yahoo.com> wrote:
> I have a text string that contains text within two brackets.
>
> e.g. "testdata[3]" "testdata[-4]", "testdata[-4g]",
>
> I wish to "extract" the string enclosed in brackets?
>
> What is a good way to do this?
>
> e.g.
>
> fun(testdata[3]) = '3'
>
> fun(testdata[-4g]) = '-4g'
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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