Try this:
> x
id snp1 snp2 snp3
1 1 A G G
2 2 G G G
3 3 G G A
> str(x)
'data.frame': 3 obs. of 4 variables:
$ id : num 1 2 3
$ snp1: Factor w/ 2 levels "A","G": 1 2 2
$ snp2: Factor w/ 1 level "G": 1 1 1
$ snp3: Factor w/ 2 levels "A","G": 2 2 1
> # test for which columns are the same
> apply(x, 2, function(.col) all(head(.col, -1) == tail(.col, -1)))
id snp1 snp2 snp3
FALSE FALSE TRUE FALSE
>
On Thu, Mar 26, 2009 at 7:15 AM, Duijvesteijn, Naomi
<naomi.duijveste...@ipg.nl> wrote:
>
> Hi Readers,
>
>
> I have a question.
>
>
> I have a large dataset and want to throw away columns that have the same
> value in the column itself and I want to know which column this was.
>
>
> For example
>
> > x<-data.frame(id=c(1,2,3), snp1=c("A","G",
> "G"),snp2=c("G","G","G"),snp3=c("G","G","A"))
>
> > x
>
> id snp1 snp2 snp3
>
> 1 1 A G G
>
> 2 2 G G G
>
> 3 3 G G A
>
>
> Now I want to know that snp2 in monomorphic (the same value for the column)
> and after I know which column it is I want to take these columns out.
>
>
> Thanks,
>
> Naomi
>
>
>
>
>
> Disclaimer: De informatie opgenomen in dit bericht (en bijlagen) kan
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--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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