[R] Rotating x-axis categorical labels

[Bill Hudspeth]

Hello,

I am using barplot to generate a histogram of population by county. I
need to plot the bars for about 35 counties, and would like to rotate
the county name labels on the x-axis to a vertical orientation so that I
can fit them all. An example of my syntax is below:

r.barplot(x,main=main,
xlab=xlab,ylab=ylab,names_arg=counties,axis_lty=1,col="lavender",ylim=r.c(0,100),cex_axis=0.7,cex_names=0.7,offset=0,las=1)

Using "las" rotates the y-axis labels --- how do I rotate the X-axis
labels...?

Thanks, William