[R] removing columns

[David Winsemius]

On May 3, 2011, at 4:24 AM, Uwe Ligges wrote:

>
>
> On 03.05.2011 13:16, nuncio m wrote:
>> Hi list,
>>
>> I have a matrix with all elements of some columns are zeroes.  Is it
>> possible to remove these columns:
>
>
> Xnew <- X[ , as.logical(colSums(X)), drop=FALSE]

A counter-example:

X <- matrix(c(1,1,1,-1,0,1,1,1,1),3)

A fix:
 > Xnew <- X[ , as.logical(colSums(abs(X))), drop=FALSE]
 > Xnew
      [,1] [,2] [,3]
[1,]    1   -1    1
[2,]    1    0    1
[3,]    1    1    1

>
> Uwe Ligges
>
>
>> and create a new matrix
>> nuncio


David Winsemius, MD
Heritage Laboratories
West Hartford, CT