mcabbott / mcabbott/AxisKeys.jl

Tables.jl `wrapdims` doesn't work on `StructArray`

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Dominant language
Julia
Stars
154
Forks
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Description

It works on DataFrame but not StructArray.

using AxisKeys, DataFrames, StructArrays

julia> wrapdims(DataFrame(a=[1,1,2,2], b=[:x, :y, :x, :y], c=[10, 20, 30, 40]), :c, :a, :b)
2-dimensional KeyedArray(NamedDimsArray(...)) with keys:
↓   a ∈ 2-element Vector{Int64}
→   b ∈ 2-element Vector{Symbol}
And data, 2×2 Matrix{Int64}:
      (:x)  (:y)
 (1)  10    20
 (2)  30    40

julia> wrapdims(StructArray(a=[1,1,2,2], b=[:x, :y, :x, :y], c=[10, 20, 30, 40]), :c, :a, :b)
ERROR: ArgumentError: wrong number of names, got (:c, :a, :b) with ndims(A) == 1
Stacktrace:
 [1] check_names(A::StructVector{@NamedTuple{…}, @NamedTuple{…}, Int64}, names::Tuple{Symbol, Symbol, Symbol})
   @ AxisKeys ~/.julia/packages/AxisKeys/sYP4R/src/wrap.jl:103
 [2] wrapdims(::StructVector{@NamedTuple{…}, @NamedTuple{…}, Int64}, ::Symbol, ::Symbol, ::Symbol)
   @ AxisKeys ~/.julia/packages/AxisKeys/sYP4R/src/wrap.jl:85
 [3] top-level scope

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the Julia reproduction in the issue and inspect AxisKeys/src/wrap.jl, especially the wrapdims and check_names paths shown in the stack trace. Compare the StructArray input with the working DataFrame case, then verify that wrapdims accepts the three names and produces the same two-dimensional keyed result for StructArray.

Written by the indexing model from the issue text.

Assessment

Tech stack
julia
Domain
data
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
45/100

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