Separate columns with constant numbers and condense them to one row in R data.frame

Question

I have a data.frame called d. In this data.frame, some columns consist of constant numbers across the rows of the first column: study.name (see bel

Answer 1

If you just want to remove repeated values across all columns unique() is base R

unique(d)

EDIT - Thanks for the clarification @CalumYou - I think this is what OP is looking for in base R.

is_constant = lapply(split(d, d$study.name), function(data){
  unlist(lapply(data,function(col){
    length(unique(col)) == 1
  }))
})
is_constant = as.data.frame(do.call(rbind, is_constant))
all_constant = d[,unlist(lapply(is_constant,all))]
all_constant = unique(all_constant)