[R] Any way to add to data frame saved as .rData file?

[Ken Termiso]

Hi all,

I've got a script that generates a few moderate-size data frames, and then 
puts them together into one big data frame at the end in order to write that 
data frame to disk, so that it may be re-opened later on...

I'm trying to trim down memory requirements in this script, so I was 
wondering if there was any way to append to a data frame already saved on 
disk (just like appending to a text file)..all the data frames here have 
identical row names; what I want to do is to tack on additional columns to a 
data frame stored in the working directory...

Alternatively, is there another data structure that would allow me to do 
this (and could preferably be converted to a data frame) ?

Thanks in advance,
Ken