[R] Beginner troubles.

[Roger Bivand]

On Thu, 26 Aug 2004, Gaute B Strokkenes wrote:

> I'm new to R.  Having read through a good chunk of "An Introduction to
> R" I'm trying to use R to do some relatively straight-forward
> (mathematically speaking) stuff.
> 
> I have a file which contains the coordinates of a set of points in
> R^3, with one point per line (i.e. three real numbers).  The aim is to
> read that file in and produce the set of all the distances between all
> possible different pairs of points in that file.  So I try:

outer() is maybe more difficult than need be, unless this isn't the real 
question. Perhaps look at dist() first - it solves your declared problem 
directly in a single command, but that makes me think your question was 
actually about outer, not distances?

Roger

> 
> > a <- read.table("FL_BR14.xyz")
> 
> > dim(a)
> [1] 329   3
> 
> > A <- function(i) a[i, ]
> 
> > A(1)
>          V1       V2       V3
> 1 -1558.364 16.97055 1004.381
> 
> > d <- function(x, y) sqrt(sum((x - y) * (x - y)))
> 
> > outer(1:length(a[, 1]), 1:length(a[, 1]), function(u, 
>     v) d(A(u), A(v)))
> Error in outer(1:length(a[, 1]), 1:length(a[, 1]), function(u, v) d(A(u),  : 
> 	dim<- : dims [product 108241] do not match the length of object [1]
> 
> This last error has me stumped.  Could anyone give me a pointer in the
> right direction?
> 
> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no