Hi Anthony,
Try this:

 x[,apply(x,2,function(x) !all(x==0))]


HTH,

Jorge


On Wed, Jan 14, 2009 at 5:01 PM, Anthony Dick <adick@uchicago.edu> wrote:

> Hello-
>
> I would like to remove the columns of a matrix that contain all zeros. For
> example, from
> x<-matrix(c(1,5,3,2,1,4,0,0,0), ncol=3,nrow=3)
>
> I would like to remove the third column. However, because this is in a loop
> I need a way to first determine which columns are all zeros, and only then
> remove them. I.e., I don't know which column of x contains all zeros until
> after x is created.
>
> Thanks!
>
> Anthony
>
> --
> Anthony Steven Dick, Ph.D.
> Post-Doctoral Fellow
> Human Neuroscience Laboratory
> Department of Neurology
> The University of Chicago
> 5841 S. Maryland Ave. MC-2030
> Chicago, IL 60637
> Phone: (773)-834-7770
> Email: adick@uchicago.edu
> Web: http://home.uchicago.edu/~adick/
>
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