Kayvan-Zahiri opened a new issue, #51046:
URL: https://github.com/apache/arrow/issues/51046
### Describe the bug, including details regarding any error messages,
version, and platform.
`pyarrow.interchange.from_dataframe` builds the dictionary array without the
`is_ordered` flag the producer reports, so an ordered categorical column comes
back unordered. A pyarrow table whose column is `dictionary(int32, string,
ordered=True)` does not survive its own round trip, and an ordered pandas
`Categorical` loses its ordering on the way in.
```python
import pyarrow as pa
from pyarrow.interchange import from_dataframe
t = pa.table({"c": pa.array(["a", "b", "a"]).dictionary_encode().cast(
pa.dictionary(pa.int32(), pa.string(), ordered=True))})
print(t.schema.field("c").type.ordered) # True
print(from_dataframe(t).schema.field("c").type.ordered) # False
```
The interchange protocol exposes the flag: a categorical column's
`describe_categorical` returns `is_ordered`, and the pandas consumer passes it
through. The pyarrow consumer reads the mapping but drops `is_ordered`.
### Component(s)
Python
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