[R] Help with apply and split...

[Mike H. Ryu]

I'm trying to drop all rows except for the ones with the most recent year.
So I split the data frame by NPERMNO and keep just the last record of all
groups.

datg=t(sapply(split(datgic, datgic$NPERMNO, drop=TRUE), function(x){return(
x[nrow(x),] )}))


I get something like this...

      GVKEY  NPERMNO GIC      year
10001 12994  10001   55102010 2007
10002 19049  10002   40101015 2007
10009 16739  10009   40101010 1999

Has this been made into a proper data frame.  How come the row numbers are
not 1,2,3,4...?

Thank you so much, and I would really appreciate any help!

Mike