sgilmore10 opened a new pull request, #37806:
URL: https://github.com/apache/arrow/pull/37806
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### Rationale for this change
Now that many of the commonly-used "primitive" array types have been added
to the MATLAB Inferface, we can implement `arrow.array.StructArray` class.
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### What changes are included in this PR?
Added `arrow.array.StructArray` MATLAB class.
*Methods* of `arrow.array.StructArray` include:
- `fromArrays(arrays, nvpairs)`
- `field(i)` -> get the `i` field as an `arrow.array.Array`. `i` can be a
positive integer or a field name.
- `toMATLAB()` -> convert to a MATLAB `table`
- `table()` -> convert to a MATLAB `table`
*Properties* of `arrow.array.StructArray` include:
- `Type`
- `Length`
- `NumFields`
- `FieldNames`
- `Valid`
**Example Usage**
```matlab
>> a = arrow.array([1, 2, 3, 4]);
>> b = arrow.array(["A", "B", "C", "D"]);
>> s = arrow.array.StructArray.fromArrays(a, b, FieldNames=["A", "B"])
s =
-- is_valid: all not null
-- child 0 type: double
[
1,
2,
3,
4
]
-- child 1 type: string
[
"A",
"B",
"C",
"D"
]
% Convert StructArray to a MATLAB table
>> t = toMATLAB(s)
t =
4×2 table
A B
_ ___
1 "A"
2 "B"
3 "C"
4 "D"
```
### Are these changes tested?
Yes. Added a new test class `tStructArray.m`
### Are there any user-facing changes?
Yes. Users can now construct an `arrow.array.StructArray` instance.
### Notes
1. Although
[`struct`](https://www.mathworks.com/help/matlab/ref/struct.html) is a MATLAB
datatype, `StructArray`'s `toMATLAB` method returns a MATLAB `table`. We went
with this design because the layout of MATLAB `table`s more closely resembles
`StructArray`s. MATLAB `tables` ensure a consistent schema and the data is laid
out in a columnar format. In a future PR, we plan on adding a `struct` method
to `StructArray`, which will return a MATLAB `struct` array.
### Future Directions
2. Add a `fromMATLAB` static method to create `StructArray`s from MATLAB
`tables` and MATLAB `struct` arrays.
3. Add a `fromTable` static method to create `StructArray`s from
`arrow.tabular.Table`s
4. Add a `fromRecordBatch` static method to create `StructArray`s from
`arrow.tabular.RecordBatch`s
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