sgilmore10 opened a new pull request, #37613:
URL: https://github.com/apache/arrow/pull/37613
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### Rationale for this change
Currently, there is no way to easily convert an `arrow.array.ChunkedArray`
into a corresponding MATLAB array, other than (1) manually iterating chunk by
chunk, (2) calling `toMATLAB` on each chunk, and then (3) concatenating all of
the converted chunks together into one contiguous MATLAB array.
It would be helpful to add a toMATLAB method to `arrow.array.ChunkedArray`
that abstracts away all of these steps.
### What changes are included in this PR?
1. Added `toMATLAB` method to `arrow.array.ChunkedArray` class
2. Added `preallocateMATLABArray` abstract method to `arrow.type.Type`
class. This method is used by the `ChunkedArray` `toMATLAB` to pre-allocate a
MATLAB array of the expected class type and shape. This is necessary to ensure
`toMATLAB` returns the correct MATLAB array when the `ChunkedArray` has zero
chunks. If `toMATLAB` stored the result of calling `toMATLAB` on each chunk in
a `cell` array before concatenating the values, `toMATLAB` would return a 0x0
`double` array for zero-chunked arrays. The pre-allocation approach avoids this
issue.
3. Implement `preallocateMATLABArray` on all `arrow.type.Type` classes.
4. Added an abstract class `arrow.type.NumericType` that all classes
representing numeric data types inherit from. `NumericType` implements
`preallocateMATLABArray` for its subclasses.
### Are these changes tested?
Yes. Added unit tests to `tChunkedArray.m`.
### Are there any user-facing changes?
Yes. Users can now call `toMATLAB` on `ChunkedArray`s.
**Example**
```matlab
>> a = arrow.array([1 2 NaN 4 5]);
>> b = arrow.array([6 7 8 9 NaN 11]);
>> c = arrow.array.ChunkedArray.fromArrays(a, b);
>> data = toMATLAB(c)
data =
1
2
NaN
4
5
6
7
8
9
NaN
11
```
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