R help - Nov 2007 - Is there a simpler way to do this?

Dear Friends,

My objective is to do element wise multiplication of two vectors. For example
suppose I have

a <- (1,1,1)
b <- (2,4)

My output should be (2,4,2,4,2,4). I managed to write it down with loops as
follows

r <- c(1,1,1)
l <- c(2,4)
x <- 1
for (j in 1:3)
{
  for (i in 1:2)
    {
      new[x,] <- r[j]*l[i]
      x <- x+1
    }
}


Is there a simpler solution to this without using the loops?


Thanks and Regards

Anup

       
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On Tue, 2007-11-20 at 17:13 -0800, Anup Nandialath
wrote:
> Dear Friends,
> 
> My objective is to do element wise multiplication of two vectors. For
example suppose I have
> 
> a <- (1,1,1)
> b <- (2,4)
> 
> My output should be (2,4,2,4,2,4). I managed to write it down with loops as
follows
> 
> r <- c(1,1,1)
> l <- c(2,4)
> x <- 1
> for (j in 1:3)
> {
>   for (i in 1:2)
>     {
>       new[x,] <- r[j]*l[i]
>       x <- x+1
>     }
> }
> 
> 
> Is there a simpler solution to this without using the loops?
> 
> 
> Thanks and Regards
> 
> Anup
Try this:
> as.vector(t(a %o% b))
[1] 2 4 2 4 2 4


See ?outer for more information.

HTH,

Marc Schwartz