same value in column-->delete
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.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
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