[R] Vector multiplication
Duncan Murdoch
murdoch at stats.uwo.ca
Wed Mar 17 22:49:38 CET 2010
On 17/03/2010 2:03 PM, Kaspar Bernet wrote:
> Hi,
>
> this may sound stupid (and it probably is), but I can't seem to find out how to multiply each element of a vector with each element of another vector where the result would be a matrix of dim[length(vectorOne),length(vectorTwo)] without using loops.
>
> example: if
>
> a -> c(1,2,3)
> b -> c(4,5,6)
>
> i'm looking for the operation that would yield:
>
> [,1] [,2] [,3]
> [1,] 4 8 12
> [2,] 5 10 15
> [3,] 6 12 18
>
> any hints are greatly appreciated,
> a <- 1:3
> b <- 4:6
> outer(a,b)
[,1] [,2] [,3]
[1,] 4 5 6
[2,] 8 10 12
[3,] 12 15 18
> outer(b,a)
[,1] [,2] [,3]
[1,] 4 8 12
[2,] 5 10 15
[3,] 6 12 18
Duncan Murdoch
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