John: I agree: the Docs are not clear on this. V&R's MASS (p.84 in the 4th edition) gives an explanation:
"Positions in the plot region may also be specified in absolute **user coordinates**. Initially user coordinates and relative coordinates [..relative to the unit square of the enclosing region--BG] coincide,, but any high-level plotting function changes the user coordinates so that the x- and y- coordinates range from their minimum to maximum values as given by the plot axes." As James said, xlim and ylim is what you want. A more extensive discussion and examples of the use of usr coordinates can be found in Paul Murrell's R GRAPHICS book, pp. 99 -105. Bert Gunter Genentech Nonclinical Statistics -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of James Sent: Friday, October 19, 2007 10:01 AM To: John Sorkin Cc: r-help@r-project.org Subject: Re: [R] controlling plot range On Oct 19, 2007, at 10:54 AM, John Sorkin wrote: > Windows XP > R 2.5.0 > I am trying to produce two plots that have the same range, i.e. x > from 50 to 400 on both plots and y from 50 to 400 on both plots. > (This will allow me to compare slopes). I have used the code below > without success using usr (I have also used xaxp and yaxp but I am > not including the code): > > plot(tgNo26[,"TGh"],tgNo26[,"TGs"],usr=c(50,400,50,400)) > plot(tgNo26[grep("CONTROL",tgNo26[,"PATIENT"]),"TGh"], > tgNo26[grep("CONTROL",tgNo26[,"PATIENT"]),"TGs"],usr=c > (50,400,50,400)) > > RESULT: > axes on first plot 50-400, y axis 50-350 > axes on second plot 50-250 y axis 100-250 From ?plot.default Are you looking for: xlim the x limits (x1, x2) of the plot. Note that x1 > x2 is allowed and leads to a "reversed axis". ylim the y limits of the plot. I believe this will allow you to set the axes to the same limits so that you can compare more easily. HTH James ______________________________________________ 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. ______________________________________________ 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.