I\'m trying to get the pairwise products of a vector, say
a = c(1,2,3,4)
What I\'m trying to get is
2,3,4,6,8,12 (in that order).<
combn() is nice for this sort of thing:
a <- 1:4 combn(a, m = 2, FUN = prod) # [1] 2 3 4 6 8 12
lower.tri selects them in that order:
lower.tri
out <- outer(1:4,1:4) out[lower.tri(out)] # [1] 2 3 4 6 8 12