Dimitris Rizopoulos wrote:
you could try something like the following:
groups <- list(gp1 = 1:3, gp2 = 4:5, gp3 = 6:7,
gp4 = 8:10, gp5 = 11)
combn(5, 2, function (x) expand.grid(groups[x]), simplify = FALSE)
combn(5, 3, function (x) expand.grid(groups[x]), simplify = FALSE)
combn(5, 4, function (x) expand.grid(groups[x]), simplify = FALSE)
and this transforms it nicely into a single matrix
y <- combn(5, 2, function (x) as.matrix(expand.grid(groups[x])),
simplify = FALSE)
Reduce(rbind, y)
Bernd
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