sgilmore10 opened a new pull request, #37998:
URL: https://github.com/apache/arrow/pull/37998
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### Rationale for this change
Right now, the only way to construct an `arrow.array.StructArray` is to call
its static method `fromArrays` method. Doing so requires users to first
construct the individual field arrays before creating the `StructArray`.
```matlab
>> a1 = arrow.array([1 2 3 4]);
>> a2 = arrow.array(["A" "B" "C" "D"]);
>> s1 = arrow.array.StructArray.fromArrays(a1, a2, FieldNames=["Number"
"String"])
s1 =
-- is_valid: all not null
-- child 0 type: double
[
1,
2,
3,
4
]
-- child 1 type: string
[
"A",
"B",
"C",
"D"
]
```
It would be nice if users could construct `StructArray`s from MATLAB
`table`s:
```matlab
>> t = table([1 2 3 4]', ["A1" "A2" "A3" "A4"]', VariableNames=["Number",
"String"])
>> s1 = arrow.array.StructArray.fromMATLAB(t)
s1 =
-- is_valid: all not null
-- child 0 type: double
[
1,
2,
3,
4
]
-- child 1 type: string
[
"A",
"B",
"C",
"D"
]
```
Additionally, adding `fromMATLAB` to `StructArray` enables returning
`StructArray`s from `arrow.array()`:
```matlab
>> t = table([1 2 3 4]', ["A1" "A2" "A3" "A4"]', VariableNames=["Number",
"String"])
>> s1 = arrow.array(t)
s1 =
-- is_valid: all not null
-- child 0 type: double
[
1,
2,
3,
4
]
-- child 1 type: string
[
"A",
"B",
"C",
"D"
]
```
### What changes are included in this PR?
1. Added static constructor method `fromMATLAB` to
`arrow.array.StructArray`. It accepts a `table` as input and optionally two
name-value pairs: `FieldNames` and `Valid`.
2. Set the `ArrayStaticConstructor` property of
`arrow.type.traits.StructTraits` to `@arrow.array.StructArray.fromMATLAB`.
Previously, it was set to `missing`.
3. Updated `arrow.type.traits.traits(className)` to return `StructTraits` if
`className` is the string `"table"`.
4. Updated `arrow.array` to accept a MATLAB `table` as input and return an
`arrow.array.StructArray` if given a `table`.
### Are these changes tested?
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Yes. Added new tests cases to `tArray.m`, `tStructArray.m`, `ttraits.m`, and
`tStructTraits.m`.
### Are there any user-facing changes?
Yes, users can now create `StructArray`s directly from MATLAB `table`s by
calling either `arrow.array()` or `arrow.array.StructArray.fromMATLAB`.
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