function - 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 below).

For example, columns ESL, ESL.1, prof, and prof.1 are constant numbers for all rows of Shin.Ellis and also constant for all rows of Trus.Hsu and so on.

Q: In BASE R, how can I separate such constant variables, and then condense them to one row with only one number?

My desired output is shown further below. A functional answer is appreciated.

d <- read.csv("https://raw.githubusercontent.com/izeh/m/master/irr.csv", h = T)[-(2:3)]

## FIRST 8 ROWS:

#    study.name ESL prof scope type ESL.1 prof.1 scope.1 type.1
# 1  Shin.Ellis   1    2     1    1     1      2       1      1
# 2  Shin.Ellis   1    2     1    1     1      2       1      1
# 3  Shin.Ellis   1    2     1    2     1      2       1      1
# 4  Shin.Ellis   1    2     1    2     1      2       1      1
# 5  Shin.Ellis   1    2    NA   NA     1      2      NA     NA
# 6  Shin.Ellis   1    2    NA   NA     1      2      NA     NA
# 7    Trus.Hsu   2    2     2    1     2      2       1      1
# 8    Trus.Hsu   2    2    NA   NA     2      2      NA     NA

Desired output:

#    study.name ESL prof  ESL.1 prof.1 
# 1  Shin.Ellis   1    2      1      2  
# 2  Trus.Hsu     2    2      2      2
# .     .         .    .      .      . # AND SO ON !!!

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)