Symbol size in plot relative to axis scale and not the graphics window

Dear all,

I am wanting to plot points that have a defined absolute size relative
to the scale of the axis.
For example, the following gives me a plot with sizes relative to the
defined "size" variable but are not of the specified absolute size
(relative to the axis)

coords<- as.data.frame(matrix(c(c(0,0),c(5,5),c(0,3)), 3, 2))

coords$radius<- c(1.4112, 2.34, 1.4573)
coords$size<- 2*coords$radius

plot(coords[,1:2], cex=coords[,4])

Hi Kirsty,
As you seem to be using the small circle (pch=1), you could use 
draw.circle (plotrix) instead. The three relevant arguments are:

x,y (x and y coordinates of the circle in user units)
radius (radius of the circle in user units)

For example:

plot(coords[,1:2],type="n")
draw.circle(coords[,1],coords[,2],coords$radius)

You can also change the color, width and line type of the circumference 
and fill the circles if you wish.

Jim