[R] Converting yr mo da to dates

[David Parkhurst]

I'm using R 2.0.1 in windows XP (and am not currently subscribed to this 
mailing list).

I have a USGS dataset, a text file with fixed width fields, that includes 
dates as 6-digit integers in the form yrmoda.  I could either read them that 
way, or with yr, mo, and da as separate integers.  In either case, I'd like 
to convert them to a form will allow plotting other "y" variables against 
the dates (with correct spacing) on the horizontal axis.

I've looked in all the manuals, but didn't find a way to do this.  I can 
copy the data to a spreadsheet, make the conversion there, and then move the 
data to R, but that's a nuisance.

I'd appreciate learning whether there is a way to do this all within R. 
Thanks.

Dave Parkhurst