[R] Equivalent of 'first.var' or 'last.var' from SAS in R?

[Matthew Pettis]

Hi,

I want to sort a data frame by multiple columns and then take the
first record in each unique level of the "by" group I used to sort the
data frame.  Does someone have an example of how to do this?

Thanks,
Matt

-- 
It is from the wellspring of our despair and the places that we are
broken that we come to repair the world.
-- Murray Waas