[R] Adding bars to the right of existing ones using barplot

[Jason Horn]

I'm trying to create a barplot that has two sets of data next to each  
other.  I'm using barplot with the add=TRUE option, but this simply  
adds the second dataset on top of the first, obscuring it.  How do I  
add the new data to the right on the existing barplot so that both  
sets are visible?  I've been playing with all sorts of option and  
reading the list archives with no luck.

Thank you anyone who has the answer.

- Jason