On Aug 19, 2012, at 5:14 PM, Dikán Szabolcs András wrote:
Dear R Users! I'm new in R! I've got a data.frame. For
example:a<-data.frame(cbind( 0:1, 1:10)) X1 X2
1 0 1
2 1 2
3 0 3
4 1 4
5 0 5
6 1 6
7 0 7
8 1 8
9 0 9
10 1 10 Firstly i want to create combinations from X2, for
example:combn(a$X2,2) It's ok,
but secondly
I would like to get combinations from those X2 numbers only , where
X1= 0. Could you help me? Thanks!
> combn( a[a$X1==0, "X2"] ,2)
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 1 1 1 3 3 3 5 5 7
[2,] 3 5 7 9 5 7 9 7 9 9
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entirety but for this case the section: "2.7 Index vectors; selecting
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