[R] Can't figure out why short figure won't work

[Frank Harrell]

I can't get the points and "a" and "b" to render correctly (they are 
squeezed into the axis) unless I make the height of the figure waste a 
lot of space.  I'd appreciate any ideas.  The code is below. Thanks!

png('/tmp/z.png', width=480, height=100)
par(mar=c(3,.5,1,.5))
plot.new()
par(usr=c(-10, 410, -.04, 1.04))
par(mgp=c(1.5,.5,0))
axis(1, at=seq(0, 400, by=50))
axis(1, at=seq(0, 400, by=25), tcl=-.25, labels=FALSE)
title(xlab='Mean Count')
points(x, rep(-.02, length(x)))
lines(rep(.25*1500, 2), c(-.04, .04), col='blue')
lines(rep(.196*1500, 2), c(-.04, .04), col='blue')
text(.25*1500, .07, 'a', col='blue')
text(.196*1500,.07, 'b', col='blue')
dev.off()

It works if I use height=350.

Frank


 > version
                _
platform       x86_64-pc-linux-gnu
arch           x86_64
os             linux-gnu
system         x86_64, linux-gnu
status
major          3
minor          0.1
year           2013
month          05
day            16
svn rev        62743
language       R
version.string R version 3.0.1 (2013-05-16)
nickname       Good Sport
 >
-- 
Frank E Harrell Jr Professor and Chairman      School of Medicine
                    Department of Biostatistics Vanderbilt University