[R] same value in column-->delete

[Duijvesteijn, Naomi]

   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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