On Aug 20, 2010, at 6:44 AM, Cecilia Carmo wrote:
Hi everyone!
I'm matching two samples to create one sample that have
pairs of observations equal for the k1 variable. Merge() doesn't
work because I dont't want to recycle the values.
When there is more than one possible match in either y or x to a
possible match on k1 in the othr set of values, is there some rule
that lets you determine which one should be chosen. Your offered
solution suggests that you think the order in the original data.frams
is a proper rule, but why should we believe that rule is anything
other than convenience?
--
David.
x <- data.frame(k1=c(1,1,2,3,3,5), k2=c(20,21,22,23,24,25))
x
y <- data.frame(k1=c(1,1,2,2,3,4,5,5), k2=c(10,11,12,13,14,15,16,17))
y
merge(x,y,by="k1")
k1 k2.x k2.y
1 1 20 10
2 1 20 11
3 1 21 10
4 1 21 11
5 2 22 12
6 2 22 13
7 3 23 14
8 3 24 14
9 5 25 16
10 5 25 17
I have a final dataframe with 10 rows, but I want it with 5 rows,
like this:
k1 k2.x k2.y
1 1 20 10
2 1 21 11
3 2 22 12
4 3 23 14
5 5 25 16
Thanks for any help.
Cecília Carmo
(Universidade de Aveiro)
David Winsemius, MD
West Hartford, CT
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