select maximum row value by group

Question

I\'ve been trying to do this with my data by looking at other posts, but I keep getting an error. My data new looks like this:

id  year    name          


        

Answer 1

ave works here yet again, and will account for a circumstance with multiple rows for the maximum year.

new[with(new, year == ave(year,id,FUN=max) ),]

#  id year  name gdp
#3  1 1982 Jamie  70
#6  2 1992  Kate  67
#9  3 1996   Joe  90