[Python] Timezone being dropped in dictionary array

[galipremsagar]

Describe the bug, including details regarding any error messages, version, and platform.

import pandas as pd
 import pyarrow as pa

 cats = pd.DatetimeIndex(["2024-01-01", "2024-01-02"]).tz_localize("US/Eastern")
 cat = pd.Categorical(values=[cats[0], cats[1], cats[0]], categories=cats)

 # pandas keeps the tz on the categories
 assert str(cat.dtype.categories.dtype) == "datetime64[us, US/Eastern]"

 arr = pa.array(cat, from_pandas=True)
 print(arr.type) # dictionary<values=timestamp[us], indices=int8, ordered=0>
 print(arr.type.value_type) # timestamp[us] ← tz dropped
 assert arr.type.value_type.tz is not None, "BUG: tz dropped from dictionary value_type"

 Contrast — the same tz-aware values convert correctly when not wrapped in a Categorical:

 pa.array(cats, from_pandas=True).type
 # timestamp[us, tz=US/Eastern] ← tz preserved

Component(s)

Python

[AlenkaF]

Thank you for opening the issue @galipremsagar.
Will have a look at the proposed solution in the linked PR today.

[AlenkaF]

@AnkitAhlawat7742 can you comment on this issue so I can assign it to you?

[AnkitAhlawat7742]

I have already submitted a fix in PR #49878 which addresses the timezone being dropped when converting tz-aware pandas.

[AlenkaF]

Issue resolved by pull request 49878
#49878