[R] Aspect ratio and limits

[Barry Rowlingson]

Suppose I have the following data I want to scatterplot:

  > xy
       [,1] [,2]
  [1,]    0    0
  [2,]   21    4

I start up a graphics window and fire away:

  > plot(xy)

  - but because the graphics window is square, the aspect ratio is 
wrong. So I add:

  > plot(xy, asp=1)

  - now the aspect ratio is correct, but the Y range is about -8 to 11, 
whereas my data has a Y range of 0 to 4. The plot appears in the middle 
of a mostly empty square. So lets try:

  > plot(xy, asp=1, ylim=c(0,4))

  - which seemingly changes nothing. The reason being that par()$pty is 
'm', which means to use as much of the plot area as possible. The only 
other option is 's' which produces a square plot. I want it to produce a 
very rectangular plot. R cant comply with all these requests.

  If I leave par(pty='m') then I can change the shape of the graphics 
window until I get the effect I want, but this seems an unsatisfactory 
way of doing it, and when I come to make a PostScript version I need to 
set the dimensions of the PS device correctly.

  Is there a right way to do this? The only way I can think is to do the 
plot without box and axes, and then add them afterwards, but that could 
get very messy. Have I missed something obvious?

Barry