[R] subsetting a matrix

[Rajarshi Guha]

On Tue, 2003-09-30 at 15:51, Jason Turner wrote:
> (Ted Harding) wrote:
> 
> > On 30-Sep-03 Rajarshi Guha wrote:
> > 
> >>Hi,
> >>  I'm trying to take a set of rows and columns out of a matrix. I hve
> >>been using the index aray approach. My overll matrix is X and is 179 x
> >>65. I want to take out 4 columns and 161 rows.
> ...
> This is documented in "An Introduction to R", under the section "Arrays 
> and Matricies".  There's lots of good stuff in there.  From R:
> 
> help.start()
> 
> And click on "An Introduction to R".
> 
> The short answer to this particular question:
> a) negative indicies remove rows or columns.  Since you only want to 
> remove 4 columns, I'd use that.
> b) Since you only want to keep 18 rows, I'd use the numbers of the rows 
> you want to keep.


Thanks for all the answers. I had been writing loops and extracting
elements - I've been spending too much time in C :-/

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