[R] R loop help

[Patrick Burns]

An aside to the main question:

I don't think that

   i+1:3

is doing what you think it is.

On 26/03/2010 23:01, casperyc wrote:
>
> Hi,
>
> I am tring to write a loop to compute this,
> ==========================
> x1=c(
> 	rep(-1,4),
> 	rep(1,4)
> 	)
>
> x2=c(
> 	rep(c(-1,-1,1,1),2)
> 	)
> 	
> x3=c(
> 	rep(c(-1,1),4)
> 	)
> 	
> x1*x2
> x1*x3
> x2*x3
> ========================
>
> suppose i have x1,x2,x3
> i want to compute their ' two factor interactions', x1x2,x1x3 and x2x3,
> I wrote
>
> ========================
> for(i in 1:2){
> 	for( j in i+1:3){
> 	xij=c()
> 	xij=xi*xj
> 	}
> }
> ========================
> it did not seem to recognize xi and xj
>
> is there any suggestion?
> it would be wonderful if there exists a single command that i can use
>
> My ultimate aim is to find the 55 xixj s of the following data:
> http://n4.nabble.com/file/n1692945/test_pic.jpg test_pic.jpg
>
>
> Thanks.

-- 
Patrick Burns
pburns at pburns.seanet.com
http://www.burns-stat.com
(home of 'Some hints for the R beginner'
and 'The R Inferno')