[R] how to extract the column name or value from the numerical value of the matrix

[Marc Schwartz (via MN)]

On Mon, 2005-09-19 at 12:30 -0700, shanmuha boopathy wrote:
> Dear sir,
>  i have a matrix like
>  x<-c(1:20)
> A<-matrix(x,4,5)
> > A
>      [,1] [,2] [,3] [,4] [,5]
> [1,]    1    5    9   13   17
> [2,]    2    6   10   14   18
> [3,]    3    7   11   15   19
> [4,]    4    8   12   16   20
> 
> I want to extract the column value for the matrix
> value 11...
> 
> or the row value for 14..
> how it is possible?
> 
> thanks for your help....
> 
> with regards,
> boopathy.


Why did you copy r-devel? r-help is the appropriate forum.


See ?which and take note of the 'arr.ind' argument:

> which(A == 11, arr.ind = TRUE)
     row col
[1,]   3   3


> which(A == 14, arr.ind = TRUE)
     row col
[1,]   2   4


HTH,

Marc Schwartz