JuliaArrays / JuliaArrays/AxisArrays.jl
Select by axis values doesn't preserve the order
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- Julia
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Description
When selecting an AxisArray by index, it returns the correct order as expected. However, if one selects by axis values, it doesn’t preserve the order (see example below).
julia> tmp = AxisArray(rand(2,3), x=[:a, :b], y=[:A, :B, :C])
2-dimensional AxisArray{Float64,2,...} with axes:
:x, [:a, :b]
:y, [:A, :B, :C]
And data, a 2×3 Array{Float64,2}:
0.373003 0.355006 0.158701
0.691354 0.277119 0.651728
julia> tmp[[2,1],:]
2-dimensional AxisArray{Float64,2,...} with axes:
:x, [:b, :a]
:y, [:A, :B, :C]
And data, a 2×3 Array{Float64,2}:
0.691354 0.277119 0.651728
0.373003 0.355006 0.158701
julia> tmp[[:b, :a],:]
2-dimensional AxisArray{Float64,2,...} with axes:
:x, [:a, :b]
:y, [:A, :B, :C]
And data, a 2×3 Array{Float64,2}:
0.373003 0.355006 0.158701
0.691354 0.277119 0.651728
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the Julia example from the issue, comparing index-based selection with selection by axis values. Trace the value-based indexing path and add or update coverage for a reversed request such as [:b, :a]; done means the returned axis values and data preserve the requested order.
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
- Mostly clear
- Newbie friendliness
- 45/100