plot multiple axis in one graph and save in R

The useful blog I found is the following:

plot multiple axis in one graph in R


The basic idea is

1	<code>> plot  <-- first plot

2

3	> par(new=T)   <-- tell R to overwrite the first plot

4

5	> plot( ..., axes=F, ... )   <-- plot our second plot, but don't touch the axes

6

</code

Also, another trick when plotting a graph first, and then save to file is the following:

plot(...)
dev.copy(svg,"*.svg")
dev.off()

http://statistics.berkeley.edu/classes/s133/saving.html