One of the best ways to learn how to code in R is to view sample scripts that people share.
I recently came across this post where Michael uses R to scrape twitter and collect all sorts of great data on the current unrest in the Middle East and northern Africa. While the post is worthy of a read itself, what I found useful was the function ?file.exists. The usage is obvious, but the help file exposed a collection of functions that I was not previously aware of.
For instance, I have used ?unlink before, but I had no idea that you could use R to create directories, walk file paths, etc. I can’t speak for SAS, but I am quite certain you can’t do this natively in SPSS.
I have to admit that I probably should have already known about this, but the ability to programmatically manipulate files and directories are the sorts of things that keep affirming that time learning R is well spent.