[R] Alter plot point size by value of the plot value

[Douglas Scheftner]

R folks,

  I am trying to create a mhtplot plot that will alter the point size via the plot point value.    The size of the point should change via a set criteria such as:

if  point value <10^-6 size 3x
else if 10^-3> point value >10^-6 size 2x
else point value >10^-3 size is x

I consider myself an R newbie, and I am assuming that I could do this via some sort of function to change the parameter cex value of the plot, but I do not even know where to begin.  I have searched for something similar to this, but have not had any luck.  Is it possible to write a function that will alter the cex value via the plot value.  Any suggestions?

Thanks in advance,
Doug