I’m currently writing some lecture notes on R and I used the phrase “a R package” without thinking. Since the word following the article “a” was a consonant, I automatically went for “a” instead of “an”. The problem is that “R” sounds likes a vowel, so “a R package” grates on the listener. The correct rule is to use “an” when the word following the article “sounds like a vowel”.
A quick google search suggests other people mess up too:
- the correct phrase “an R package” – around 600, 000 hits;
- the incorrect phrase “a R package” – around 150,000 hits.
Who would have thought that people could be wrong on the Internet…

FWIW, this makes no sense to people from across the pond. We have a perfectly nice consonant sound for “R”, and “An R Package” is definitely the way to go. I sympathize with your dialect’s shortcomings, though.
Comment by Harlan — March 26, 2011 @ 7:07 pm
I suppose my R’s are a little over expressed since I’m originally from Glasgow – I can provide a translation if needed!
Surely if you have a nice consonant sound for “R”, then you would use “a R package”? You wouldn’t say “an royal wedding”. FWIW, you spelt sympathise incorrectly
Comment by csgillespie — March 26, 2011 @ 8:16 pm
Whether to use “a” or “an” is based on phonetics of the following word, not its spelling (although you will find plenty of sources that incorrectly state that the decision is based on spelling). An R package is correct. A R package is wrong.
Comment by G. Grothendieck — March 27, 2011 @ 1:57 am
I completely agree – that’s what I was trying to get across. An nice example of when to use “a” with vowel is “a one armed man”, as “an one armed man” just sounds strange.
Comment by csgillespie — March 27, 2011 @ 9:59 am