[R] Help in creating a matrix

S Ellison S.Ellison at LGCGroup.com
Thu Apr 12 13:46:31 CEST 2012


>I have dataset with n variables, say n =3  x y z
>the formula should be form = x+y+z+x*x +x*y+x*z +y*y + y*z+z*z
>my code has to for  loop
>Is there any way  to reduce two loops
>  for (i in 1:n)
>  {
>      for (j in i:n)
>     {
>        dat= cbind(dat,dat[,i]*dat[,j])
>      }
>   }


Yes; use outer

But 
- Why only two levels of looping for three variables?
- What have i, j and dat to do with the formula? 
- Why doesnt the formula appear anywhere in the loop?


-----
Thanks in Advance
        Arun
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