How to force axis to have the same range

Sebastien Bihorel <Sebastien.Bihorel <at> cognigencorp.com> writes:

I am trying to produce (standard and trellis) scatterplots which  
use the
same range of the x and y axes. In addition, I would like the plots  
to
be physically square. Is there one or more specific argument(s) to  
plot
and xyplot what would do that? I have looked at various  
combinations of
asp and pin value, but could not get what I wanted..

In lattice : aspect = 1

To satisfy both of his requests with xyplot, I think he also needs  
xlim and ylim:

  xy <-data.frame(x=1:10, y= rnorm(10)+5)
  xyplot(y ~ x, data=xy, aspect=1)
  xyplot(y ~ x, data=xy, aspect=1, ylim=c(0,11), xlim=c(0,11))

I was less successful in using xlim and ylim with plot, since it seems  
to handle the x-axis differently than the y-axis as far as padding out  
beyond the limits. I would typically need to set asp=0.85 to get what  
looked to ba a square plot. Suggest reading the documentation for  
plot.window() as a start.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT