extracting the last row of each group in a data frame

Thanks to all who helped. These are all great suggestions. 

Jeff

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: Monday, November 16, 2009 6:27 PM
To: Hao Cen
Cc: r-help at r-project.org
Subject: Re: [R] extracting the last row of each group in a data frame

Try this:

aggregate(DF[-1], DF[1], tail, 1)

Name Value
1    A     3
2    B     8
3    C     2
4    D     3

Hi,

I would like to extract the last row of each group in a data frame.

The data frame is as follows

Name Value
A 1
A 2
A 3
B 4
B 8
C 2
D 3

I would like to get a data frame as
Name Value
A 3
B 8
C 2
D 3

Thank you for your suggestions in advance

Jeff

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide

http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.