[R] writing a function

[Johannes Hüsing]

mohamed nur anisah <nuranisah_mohamed at yahoo.com> [Fri, Feb 08, 2008 at 04:42:41PM CET]:
> Dear lists,
>    
>   I'm in my process of learning of writing a function. I tried to write a simple functions of a matrix and a vector. Here are the codes:
>    
>   mm<-function(m,n){              #matrix function    
>  w<-matrix(nrow=m, ncol=n)
>  for(i in 1:m){
>   for(j in 1:n){
>    w[i,j]=i+j
>   }
>  }
> return(w[i,j])
> }
>    

In addition to the other comments, allow me to remark that 
R provides a lot of convenience functions on vectors that
make explicit looping unnecessary. An error such as yours
wouldn't have occurred to a more experienced expRt because
indices wouldn't turn up in the code at all:

mm <- function(m, n) {
    a <- array(nrow=m, ncol=n)
    row(a)+col(a)
}

Greetings


Johannes

-- 
Johannes Hüsing               There is something fascinating about science. 
                              One gets such wholesale returns of conjecture 
mailto:johannes at huesing.name  from such a trifling investment of fact.                
http://derwisch.wikidot.com         (Mark Twain, "Life on the Mississippi")