JuliaData
Request @rsubset_rtransform
Apply an @rtransform block to a restricted set of rows. Fill other rows with existing value or missing for new columns.
@chain begin
DataFrame( A = 1:4, B=[1,1,2,2] )
@rsubset_rtransform (:B == 1) begin
:A = 10
:C = 20
end
end
#result
DataFrame( A=[10,10,3,4], B=[1,1,2,2], C=[20,20,missing,missing])
Current:
julia> @chain DataFrame(A=1:4, B=[1,1,2,2]) begin
@rsubset begin
:B == 1
@kwarg view=true
end
@rtransform! begin
:A = 10
:C = 20
end
parent
end
4×3 DataFrame
Row │ A B C
│ Int64 Int64 Int64?
─────┼───────────────────────
1 │ 10 1 20
2 │ 10 1 20
3 │ 3 2 missing
4 │ 4 2 missing
Thanks Bogumil. I'll probably lay it out as:
@chain DataFrame(A=1:4, B=[1,1,2,2]) begin
@rsubset(:B == 1; view=true ); @rtransform! begin
:A = 10
:C = 20
end; parent
end
I have 5 or so of these subset blocks within a larger @rtransform block. So don't want to have too many lines opening and closing each block.
Can you do the same with a group-by? Have an @rtransform block for each value of :B That might reduce the amount of code needed to begin. each block
@rsubset(:B == 1; view=true )
it does not work AFAICT. You need @kwarg but maybe please double check.
group-by should work, but could you please show the code and output you have in mind to make sure we are on the same page.?
I absolutely want to implement this, ideally with the syntax
@rtransform df @when(:x == 1) :y = :z * 100
or
@rtransform df @when(:x == 1) begin
:y = :z * 100
:a = :b * 5
end
In the background we would have something along the lines of
@chain df begin
copy
@rsubset(:x == 1; view = true)
@rtransform! begin
:y = :z * 100
:a = :b * 5
end
parent
end
This is very feasible, I just haven't written it.
