Symbol Causes Trouble in @transform!

[ParadaCarleton]

It looks like when I try to use Symbol(x) to represent a column in transform, it causes trouble, e.g.

julia> @transform!(post_cycles, :residuals=:two_party_vote - Symbol("50.0%"))
ERROR: MethodError: no method matching -(::Vector{Float64}, ::Symbol)
Closest candidates are:
  -(::Array, ::SparseArrays.AbstractSparseMatrixCSC) at /usr/share/julia/stdlib/v1.7/SparseArrays/src/sparsematrix.jl:1777
  -(::Array{T, N}, ::FillArrays.Zeros{V, N}) where {T, V, N} at ~/.julia/packages/FillArrays/5Arin/src/fillalgebra.jl:241
  -(::ChainRulesCore.AbstractThunk, ::Any) at ~/.julia/packages/ChainRulesCore/GUvJT/src/tangent_types/thunks.jl:30
  ...
Stacktrace:
  [1] (::var"#83#84")(506::Vector{Float64})
    @ Main ~/.julia/packages/DataFramesMeta/kWkhX/src/parsing.jl:272
  [2] _transformation_helper(df::DataFrame, col_idx::Int64, ::Base.RefValue{Any})
    @ DataFrames ~/.julia/packages/DataFrames/zqFGs/src/abstractdataframe/selection.jl:538
  [3] select_transform!(::Base.RefValue{Any}, df::DataFrame, newdf::DataFrame, transformed_cols::Set{Symbol}, copycols::Bool, allow_resizing_newdf::Base.RefValue{Bool}, column_to_copy::BitVector)
    @ DataFrames ~/.julia/packages/DataFrames/zqFGs/src/abstractdataframe/selection.jl:764

After renaming the column and using :median, it works fine.

[pdeffebach]

Yes. That is expected. To refer to a column programatically, you should escape with $, i.e. Symbol doesn't cut it.

@transform!(post_cycles, :residuals=:two_party_vote - $(Symbol("50.0%")))

but you can use strings directly here.

@transform!(post_cycles, :residuals=:two_party_vote - $"50.0%")

PS, you can also omit the parentheses if you want

@transform! post_cycles :residuals=:two_party_vote - $"50.0%"

and ensure it's row-wise

@rtransform! post_cycles :residuals=:two_party_vote - $"50.0%"