Dropping multiple columns

[permanentrance]

Is there a way of dropping multiple columns with @chain?

For example, I could chain multiple calls to select and that would work:

df = DataFrame(a = repeat(1:4, outer = 2), b = repeat(2:-1:1, outer = 4), c = 1:8);
@chain df begin
  select(Not(:a))
  select(Not(:b))
end

But I was wondering if there is a cleaner way of doing it, maybe with @select ?

[pdeffebach]

Yes, you can wrap it in cols, i.t. @select(df, cols(Not(:a))

julia> @chain df begin
         @select(cols(Not(:a)))
         @select(cols(Not(:b)))
       end
8×1 DataFrame
 Row │ c
     │ Int64
─────┼───────
   1 │     1
   2 │     2
   3 │     3
   4 │     4
   5 │     5
   6 │     6
   7 │     7
   8 │     8

This is ugly syntax, but soon cols will be replaced by $, so it will look less noisy. The PR has already been merged into master here.

[bkamins]

Also note you can just write Not([:a, :b]) if this is something you are looking for.

In DataFrames.jl we try to ensure that what provide is fully composable. Here - it means that you can throw ANY column selector as an argumen to Not.

[pdeffebach]

ref #283

[pdeffebach]

Closed to focus on #283