[R] Remove columns

[Paul Hiemstra]

Hi,

This line of code does the trick:

a[,which(apply(a, 2, sum) != 0)]

cheers,
Paul

Alberto Lora M wrote:
> Hi Everbody
>
> Could somebody help me.?
>
> I need to remove the columns where the sum of it components is equal to
> zero.
>
> For example
>
>   
>> a<-matrix(c(0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,1,1,0,0,1,0), ncol=4)
>> a
>>     
>      [,1] [,2] [,3] [,4]
> [1,]    0    0    0    1
> [2,]    0    1    0    1
> [3,]    0    0    0    0
> [4,]    0    1    0    0
> [5,]    0    0    0    1
> [6,]    0    0    0    0
>
> Columns 1 and 3 should be removed
>
> the result should be the dollowing matrix
>
>      [,2]  [,4]
> [1,]    0    1
> [2,]    1    1
> [3,]    0    0
> [4,]    1    0
> [5,]    0    1
> [6,]    0    0
>
> Thanks again
>
>
>   
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-- 
Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
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