R help - Sep 2013 - Subcripting matrix

Hello again,

I have one question on subscripting matrix. Let say I have following matrix:
> Mat <- matrix(1:9, 3)
> colnames(Mat) <- c("a", "b", "a")
> Mat
     a b a
[1,] 1 4 7
[2,] 2 5 8
[3,] 3 6 9


Now I want to fetch data for colnames 'a'.I did following:
> Mat[, "a"]
[1] 1 2 3


However it is not taking second 'a' colume. Basically I expected to
get 1st and 3rd columns

Can somebody tell me how to achieve that?

Thanks and regards,

On 20-09-2013, at 12:52, Christofer Bogaso <bogaso.christofer at
gmail.com> wrote:
> Hello again,
> 
> I have one question on subscripting matrix. Let say I have following
matrix:
> 
>> Mat <- matrix(1:9, 3)
>> colnames(Mat) <- c("a", "b", "a")
>> Mat
>     a b a
> [1,] 1 4 7
> [2,] 2 5 8
> [3,] 3 6 9
> 
> 
> Now I want to fetch data for colnames 'a'.I did following:
> 
>> Mat[, "a"]
> [1] 1 2 3
> 
> 
> However it is not taking second 'a' colume. Basically I expected to
> get 1st and 3rd columns
> 
> Can somebody tell me how to achieve that?
> 
I think this is just silly.

How about

Mat[,which(colnames(Mat)=="a")]

Berend

Hi,

it seems the following works as needed...

Mat[,colnames(Mat)=="a"]

Olivier.

On Fri, 20 Sep 2013 16:22:37 +0530
Christofer Bogaso <bogaso.christofer at gmail.com> wrote:
> Hello again,
> 
> I have one question on subscripting matrix. Let say I have following
> matrix:
> 
> > Mat <- matrix(1:9, 3)
> > colnames(Mat) <- c("a", "b", "a")
> > Mat
>      a b a
> [1,] 1 4 7
> [2,] 2 5 8
> [3,] 3 6 9
> 
> 
> Now I want to fetch data for colnames 'a'.I did following:
> 
> > Mat[, "a"]
> [1] 1 2 3
> 
> 
> However it is not taking second 'a' colume. Basically I expected to
> get 1st and 3rd columns
> 
> Can somebody tell me how to achieve that?
> 
> Thanks and regards,
> 
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html and provide commented,
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-- 
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  Laboratoire de Linguistique -- EA3827
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