same value in column-->delete
On Thu, Mar 26, 2009 at 12:15 PM, Duijvesteijn, Naomi
<Naomi.Duijvesteijn at 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
Another, perhaps slightly more intuitive solution than Jim's would be
the following:
x<-data.frame(id=c(1,2,3), snp1=c("A","G",
"G"),snp2=c("G","G","G"),snp3=c("G","G","A"))
is.monovalued<-function(df){
sapply(df,function(x){
length(unique(x))==1
})
}
monovaluedCols<-is.monovalued(x)
which(monovaluedCols)
x[!monovaluedCols]
/Gustaf
Gustaf Rydevik, M.Sci. tel: +46(0)703 051 451 address:Essingetorget 40,112 66 Stockholm, SE skype:gustaf_rydevik