The GUI defaults on japanese in my environment.

Charles,

I am using the R GUI on a powermac G5 running Tiger, and despite  
having selected English as a language in the systems preferences,  
the GUI tries to speak to me in Japanese. It is a very aware GUI,  
for it may have smelled the flagrance of green tea on my desk, as I  
am indeed geographically localised in Japan. However, I am not  
expert enough in japanese to read error messages...

More seriously, I figured out that it uses the "Region" information  
in the "Format" tab of the "International" section of the  
preferences, which I set to japanese to have the dates and  
currencies japanese-style. I would be inclined to call this a bug,  
but maybe it is an intentionnal behaviour?

Yes. By default the region setting defines the language used by R.  
This behavior is rooted in the fact that it is the only valid locale  
information that can be reliably obtained from the OS. There is,  
however, a work-around for such specific cases where the region  
information contradicts the language setting, namely the locale can  
be set regardless of the system setting. For example if you wish to  
use US-english locale, you can force the GUI to do so by writing in  
the Terminal:

defaults write org.R-project.R force.LANG en_US.UTF-8

The only requirement is that the locale must use UTF-8, otherwise  
many things will break. In addition to that, it is always possible to  
use the corresponding LC_xx environment variables if finely-grained  
control over the locale is desired.

Cheers,
Simon