On Mar 29, 2011, at 3:40 PM, Lisa wrote:
Dear All,
I have a dataset that looks like this:
group subject result v4 v5
1 1 1 0 1 0
2 1 2 1 0 0
3 1 3 0 0 0
4 1 4 1 0 0
5 2 1 0 1 1
6 2 2 0 0 1
7 2 3 0 1 1
8 3 1 0 1 0
9 3 2 0 0 1
10 3 3 1 0 0
11 3 4 0 1 0
12 4 1 1 0 0
13 4 2 1 1 0
14 4 3 0 0 1
15 4 4 0 0 0
16 4 5 1 0 1
……
I only show 4 groups here. There are several subjects within each
group. I
want to select some groups in which for the firs two subjects, the
results
are equal to 0, and for the other subjects, only one has the result
being
equal to 1. So, for the data above, only the group 3 satisfies these
conditions. Therefore, the new dataset is:
group subject result v4 v5
8 3 1 0 1 0
9 3 2 0 0 1
10 3 3 1 0 0
11 3 4 0 1 0
> dfrm$sel <- ave(dfrm$result, dfrm$group, FUN=function(x) x[1]==0
&x[2]==0 & sum(x[3:length(x)]==1)==1)
> dfrm$sel
[1] 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0
> dfrm
group subject result v4 v5 sel
1 1 1 0 1 0 0
2 1 2 1 0 0 0
3 1 3 0 0 0 0
4 1 4 1 0 0 0
5 2 1 0 1 1 0
6 2 2 0 0 1 0
7 2 3 0 1 1 0
8 3 1 0 1 0 1
9 3 2 0 0 1 1
10 3 3 1 0 0 1
11 3 4 0 1 0 1
12 4 1 1 0 0 0
13 4 2 1 1 0 0
14 4 3 0 0 1 0
15 4 4 0 0 0 0
16 4 5 1 0 1 0
Using `subset` should be trivial from this point.
--
David Winsemius, MD
West Hartford, CT
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