On Nov 16, 2009, at 2:42 PM, Hao Cen wrote:
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
by(dfname$Value, dfname$Name, tail, 1) #which gets you a list
Or:
aggregate(dfname$Value, list(dfname$Name), tail, 1) #which returns a
data.frame
Group.1 x
1 A 3
2 B 8
3 C 2
4 D 3
I would like to get a data frame as
Name Value
A 3
B 8
C 2
D 3
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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