apache / apache/arrow-julia

Can't round-trip integer CategoricalArrays

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Dominant language
Julia
Stars
312
Forks
78
PR merge metrics
No merged PRs in 30d

Description

```jl
julia> using CategoricalArrays, DataFrames, Arrow
julia> Arrow.write("/tmp/my.arrow",DataFrame(x=CategoricalArray([1,2,3])))
"/tmp/my.arrow"

julia> DataFrame(Arrow.Table("/tmp/my.arrow")).x|>eltype
Int64

[69666777] Arrow v2.3.0
```

Contributor guide

No contributing guide indexed for this repository

Research direction

Start by reproducing the Julia example using CategoricalArrays, DataFrames, and Arrow.write/Arrow.Table, then trace how the categorical column is serialized and reconstructed. Done means an integer CategoricalArray survives the Arrow round trip with its categorical type preserved rather than becoming Int64.

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
35/100

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