[R] Editing Strings in R

[Marc Schwartz]

On Thu, 2004-07-29 at 21:08, Gabor Grothendieck wrote:
> Bulutoglu Dursun A Civ AFIT/ENC <Dursun.Bulutoglu <at> afit.edu> writes:
> 
> > 
> > 	I was wondering if there is a way of editting strings in R. I
> > have a set of strings and each set is a row of numbers and paranthesis.
> > 	For example the first row is: 
> > 	(0 2)(3 4)(7 9)(5 9)(1 5)
> > 	and I have a thousand or so such rows. I was wondering how I
> > could get the corresponding string obtained by adding 1 to all the
> > numbers in the string above.
> 
> First do the 1 character translations simultaneously using chartr and
> then use gsub for the remaining one to two character translation:
> 
> gsub("0","10",chartr("0123456789","1234567890","(0 2)(3 4)(7 9)(5 9)(1 5)"))


Gabor, 

One problem:  Multi-digit numbers in the source string:

> gsub("0","10",chartr("0123456789","1234567890",
       "(10 99)(3 4)(7 9)(5 9)(1 5)"))
[1] "(21 1010)(4 5)(8 10)(6 10)(2 6)"


Note the first number "10" gets transformed to "21" and the "99" goes to
"1010".


I made a quick update to NewRow, which is not faster, but gets it to two
lines, instead of three, and is a bit cleaner:

NewRow <- function(x)
{
  TempMat <- matrix(as.numeric(unlist(strsplit(x, "([\\(\\) ])"))), 
                    ncol = 3, byrow = TRUE) + 1

  paste("(", TempMat[, 2], " ", TempMat[, 3], ")", sep = "", 
        collapse = "")
}


Note that with multi digit numbers, it gives a correct result:

> NewRow("(10 99)(101 4)(7 9)(5 9)(1 5)")
[1] "(11 100)(102 5)(8 10)(6 10)(2 6)"


HTH,

Marc Schwartz