I have a DataFrame
df = DataFrame(x = 1:3, y = 4:6)
3×2 DataFrame
Row │ x y
│ Int64 Int64
─────┼──────────────
1 │ 1 4
2 │ 2 5
3 │ 3 6
How can I extract one of the columns as a Vector?
I know I can do df[:,:x] or df.x, but is there a way to do it with a function instead? The reason I am asking is that I work with the Chain.jl package and would like to do something like
@chain df begin
some_manipulations_here
pull(:x)
end
You can do one of the the following:
julia> df = DataFrame(x = 1:3, y = 4:6)
3×2 DataFrame
Row │ x y
│ Int64 Int64
─────┼──────────────
1 │ 1 4
2 │ 2 5
3 │ 3 6
julia> @chain df begin
_.x
end
3-element Vector{Int64}:
1
2
3
julia> @chain df begin
getproperty(:x) # same as above
end
3-element Vector{Int64}:
1
2
3
julia> @chain df begin
getindex(!, :x) # also _[!, :x]
end
3-element Vector{Int64}:
1
2
3
julia> @chain df begin
getindex(:, :x) # also _[:, :x]
end
3-element Vector{Int64}:
1
2
3
Probably the first option (with _.x is the simplest in practice.
I have shown the other options to highlight that all special syntaxes like df.x or df[!, :x] are actually function calls, and the special syntax is just a convenience.
OK, so one solution is
@chain df begin
some_manipulations_here
_ |> df -> df.x
end
but I actually hope that someone can come up with a cleaner solution.