R help - Jun 2009 - need help with strsplit function

Hi, if I have this string: "a.b.c.d" and I use this function:
unlist(strsplit("a.b.c.d", "\\.")), I get this as my output:
"a", "b", "c",
and "d". Is there a way to just split on the first period so I obtain
only
two pieces like: "a" and "b.c.d"? Anyways, thanks in
advance!
-- 
View this message in context:
http://www.nabble.com/need-help-with-strsplit-function-tp23983888p23983888.html
Sent from the R help mailing list archive at Nabble.com.

Using strapply in gsubfn we can match by contents rather than
delimiter.  Parentheses in the regular expression
surround captured portions.  The first such captured portion is
any string not containing a dot.  We then follow that by matching
a dot and a second captured expression which is anything.
c just concatenates the captured strings into a vector of strings.
> x <- "a.b.c.d"
> library(gsubfn)
Loading required package: proto
> strapply(x, "([^.]*)[.](.*)", c)
[[1]]
[1] "a"     "b.c.d"


On Thu, Jun 11, 2009 at 11:44 AM, njhuang86<njhuang86 at yahoo.com>
wrote:
>
> Hi, if I have this string: "a.b.c.d" and I use this function:
> unlist(strsplit("a.b.c.d", "\\.")), I get this as my
output: "a", "b", "c",
> and "d". Is there a way to just split on the first period so I
obtain only
> two pieces like: "a" and "b.c.d"? Anyways, thanks in
advance!
> --
> View this message in context:
http://www.nabble.com/need-help-with-strsplit-function-tp23983888p23983888.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>

On Jun 11, 2009, at 10:44 AM, njhuang86 wrote:
>
> Hi, if I have this string: "a.b.c.d" and I use this function:
> unlist(strsplit("a.b.c.d", "\\.")), I get this as my
output: "a",
> "b", "c",
> and "d". Is there a way to just split on the first period so I  
> obtain only
> two pieces like: "a" and "b.c.d"? Anyways, thanks in
advance!

Try this:

 > strsplit(sub("\\.", "*", "a.b.c.d"),
"\\*")
[[1]]
[1] "a"     "b.c.d"


The inner sub() replaces the first '.' with a '*' allowing you
to
split on the unique character. You can modify the replacement  
character as your data may actually require.

HTH,

Marc Schwartz