ColSpec is broken for ZScore

[juliohm]

MWE:

using TableTransforms

(a=rand(Int,3), b=rand(3)) |> ZScore(:b)

AssertionError: columns must hold continuous variables

assert_continuous(::NamedTuple{(:a, :b), Tuple{Vector{Int64}, Vector{Float64}}})@assertions.jl:8
applyfeat(::TableTransforms.ZScore{TableTransforms.NameSpec}, ::NamedTuple{(:a, :b), Tuple{Vector{Int64}, Vector{Float64}}}, ::Nothing)@transforms.jl:175
apply@transforms.jl:131[inlined]
Transform@interface.jl:84[inlined]
|>(::NamedTuple{(:a, :b), Tuple{Vector{Int64}, Vector{Float64}}}, ::TableTransforms.ZScore{TableTransforms.NameSpec})@operators.jl:911
top-level scope@[Local: 1](http://localhost:1234/edit?id=ad9e29a0-74c7-11ed-38ee-0ffbf894998f#)[inlined]

[vickydeka]

I think this is causing an error because the ZScore function only works on continuous variables and Int is a categorical variable.

Maybe the transform function can be use to apply the ZScore transformation only to the b column of the NamedTuple, and to remove the a column from the result.

using TableTransforms

(a=rand(Int,3), b=rand(3)) |> transform(:b, ZScore)

[juliohm]

The root of the issue is known, the fallback method for all ColwiseTransform types is performing assertions in the input table instead of in the selection.

Do you want to give it a try and fix it @vickydeka ? Here is the relevant function to modify:

https://github.com/JuliaML/TableTransforms.jl/blob/976ce71bf7dad543d70d18120323126fad3395d3/src/transforms.jl#L172-L208

[vickydeka]

@juliohm I would definitely like to give it a try!

[juliohm]

Fixed by #160