HI,
here is another solution:

int <- sample(1:20,10)
int
 [1] 10  4  5  2 14 17  9 11 16 13

mat<-matrix(11:30,ncol=4)
 mat
     [,1] [,2] [,3] [,4]
[1,]   11   16   21   26
[2,]   12   17   22   27
[3,]   13   18   23   28
[4,]   14   19   24   29
[5,]   15   20   25   30

 mat[apply(mat,1, function(x) any(int==x[1])),]
   [,1] [,2] [,3] [,4]
[1,]   11   16   21   26
[2,]   13   18   23   28
[3,]   14   19   24   29

Andrija


On Sat, Apr 2, 2011 at 7:08 AM, Joseph N. Paulson
<josephpaulson@gmail.com>wrote:

> Hi all!
>
> I have a vector, let's say for example int <- sample(1:20,10);
> for now:
>
> now I have a matrix...
> M = m x n
> where the first column is a "feature" column and most likely shares at
> least
> one of the int (interesting) numbers.
>
> I want to extract the rows where int[] = M[,1]
>
> I thought:
> rownames(int)<-int;
> rownames(M)<-M[,1];
>
> M[rownames(int),] would work, but it doesn't... (I assume because I have
> rownames(int) that are not found in M[,1]. Neither does,
> rownames(M)==rownames(int)...
>
> Any help would be greatly appreciated!
>
> Thank you!
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]

