[R] asp=1 and aspect ratio

[Robin Hankin]

Hi everyone

I want a square scatterplot with abline(0,1) going exactly through the
SW and NE corners.  By "square" I mean that the plotting region is
exactly square, and that the axis limits are identical.

x <- 1:20
y <- x+rep(c(-1,1),10)
lims <- range(c(x,y))

None of the following do this:

plot(x,y) ; abline(0,1)         #not square
plot(x,y,asp=1);abline(0,1)     #diagonal line misses corners

plot(x,y,asp=1,xaxs="i",yaxs="i");abline(0,1)
#diagonal line misses corners

plot(x,y,xaxs="i",yaxs="i");abline(0,1)
#not square and diag misses corners

plot(x,y,xlim=lims,ylim=lims,xaxs="i",yaxs="i");abline(0,1)
#not square

plot(x,y,asp=1,xlim=lims,ylim=lims,xaxs="i",yaxs="i");abline(0,1)
#not square (plotting region about 8cm by 9.5cm)



If I wrap the above lines in

postscript(file="foo.ps", width=5,height=5)
[...snip...]
dev.off()

then still none of the plots is exactly right [either one or both
corners are missed, or the aspect ratio off].  What am I missing?




-- 
Robin Hankin
Uncertainty Analyst
Southampton Oceanography Centre
SO14 3ZH
tel +44(0)23-8059-7743
initialDOTsurname at soc.soton.ac.uk (edit in obvious way; spam precaution)