Re: [R] Matrix manipulation

From: andrija djurovic <djandrija_at_gmail.com>
Date: Sat, 02 Apr 2011 08:33:56 +0200

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_at_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]]
>
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>

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