jorisvandenbossche commented on issue #40128:
URL: https://github.com/apache/arrow/issues/40128#issuecomment-1954172837
I am not sure if we actually have many scalar kernels apart from `cast` that
would work for dictionary ànd return dictionary?
Checking some non-scalar (vector) kernels, those seem to preserve the
dictionary correctly for empty input (using `arr` from the top post):
```
In [8]: pc.filter(arr[:0], pa.array([], pa.bool_()))
Out[8]:
<pyarrow.lib.DictionaryArray object at 0x7f2f399f2ff0>
-- dictionary:
[
"foo",
"bar"
]
-- indices:
[]
In [9]: pc.take(arr[:0], pa.array([], pa.int64()))
Out[9]:
<pyarrow.lib.DictionaryArray object at 0x7f2f3b048040>
-- dictionary:
[
"foo",
"bar"
]
-- indices:
[]
```
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