[R] matrix

[Peter Langfelder]

On Tue, Apr 26, 2011 at 2:28 PM, Val <valkremk at gmail.com> wrote:
> Hi all,
>
> Assume I have a matrix
> xv=  [1 0 0 0 0 12,
>      0 1 0 0 0 10,
>  *    0 0 1 0 0 -9,*
>      0 0 0 1 0 20,
>    *  0 0 0 0 1 -5]*
>
> if the last column of "xv"  less than  0 then I want to set zero the entire
> row.
> The desired output looks like the following. In this case row 3 and row 5
> are set zero.
>
>    [ 1 0 0 0 0 12,
>      0 1 0 0 0 10,
>     * 0 0 0 0 0 0,*
>      0 0 0 1 0 20,
>    *  0 0 0 0 0 0*]
>
> I used ifelse command but did not work
>
> Is there another command to do that?

Yes.

nc = ncol(xv)
result = xv;
result[ xv[, nc] <0, ] = 0

HTH,

Peter