[R] Index of item in matrix

[Roger Bivand]

On Wed, 2 Apr 2003, John Janmaat wrote:

> Hello All,
> 
> Is there a fast way to find the index(row and column) of a point in a 
> matrix?

> x <- matrix(rnorm(25), 5, 5)
> which(x < -1, arr.ind=TRUE)
     row col
[1,]   1   1
[2,]   2   1
[3,]   2   2
[4,]   5   2
[5,]   1   3
[6,]   2   4

-- 
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