plot: abline() - define line length

Hi,

is there a way to define, that a line drawn via abline() should only go from
for example -2 to 1 on the x-axis (with something working similiar to
xlim()) ?

thanks for any help!

I use this function (a lot):

ablinepiece <- function(a=NULL,b=NULL,reg=NULL,from,to,...){

   # Borrowed from abline
   if (!is.null(reg)) a <- reg

   if (!is.null(a) && is.list(a)) {
           temp <- as.vector(coefficients(a))

       if (length(temp) == 1) {
           a <- 0
           b <- temp
       }
       else {
           a <- temp[1]
           b <- temp[2]
       }
   }

   segments(x0=from,x1=to,
            y0=a+from*b,y1=a+to*b,...)

}



-------------------------------------------------
Remko Duursma
Post-Doctoral Fellow

Centre for Plant and Food Science
University of Western Sydney
Hawkesbury Campus
Richmond NSW 2753

Dept of Biological Science
Macquarie University
North Ryde NSW 2109
Australia

Mobile: +61 (0)422 096908



On Thu, Jan 22, 2009 at 11:01 AM, J?rg Gro? <joerg at licht-malerei.de>  
wrote:

Hi,

is there a way to define, that a line drawn via abline() should  
only go from
for example -2 to 1 on the x-axis (with something working similiar to
xlim()) ?

thanks for any help!