this works
which.is.not.unique <- apply(x,2,function(x)ifelse(length(unique(x))==1,F,T))
x[,which.is.not.unique]
patrizio
2009/3/26 Duijvesteijn, Naomi <naomi.duijveste...@ipg.nl>:
>
> 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
>
>
>
>
>
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