Paul Balanca created ARROW-8010:
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Summary: [Python] Fixed size list not convertible to Numpy Array
Key: ARROW-8010
URL: https://issues.apache.org/jira/browse/ARROW-8010
Project: Apache Arrow
Issue Type: Improvement
Components: Python
Affects Versions: 0.16.0
Environment: Ubuntu 19.10 + python 3.7
Reporter: Paul Balanca
Fixed size list of base types (i.e. int, float, ...) are not convertible to
Numpy array.
The following code:
{code:java}
t = pa.list_(pa.float32(), 2)
arr = pa.array([[1, 2], [3, 4], [5, 6]], type=t)
arr.to_numpy(){code}
raises a not implemented Arrow error as there is no Pandas block equivalent.
It sounds reasonable that the conversion to Pandas fails, but I would expect a
natural conversion to Numpy Array, as according to the Fixed Size List Layout
([https://arrow.apache.org/docs/format/Columnar.html#]), the former could be
mapped to a 2-dimensional row major matrix (e.g. 3x2 in the previous example).
This form of memory representation is quite natural if ones wants to use Apache
Arrow for in-memory collection of 2D/3D points, where we wish to have
coordinates contiguous in memory.
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