R pairwise product

前端 未结 2 1719
庸人自扰
庸人自扰 2021-01-18 15:25

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).<

相关标签:
2条回答
  • 2021-01-18 15:58

    combn() is nice for this sort of thing:

    a <- 1:4
    
    combn(a, m = 2, FUN = prod) 
    # [1]  2  3  4  6  8 12
    
    0 讨论(0)
  • 2021-01-18 16:02

    lower.tri selects them in that order:

    out <- outer(1:4,1:4)
    out[lower.tri(out)]
    # [1]  2  3  4  6  8 12
    
    0 讨论(0)
提交回复
热议问题