DOC: mention .attrs are preserved in Parquet IO for pyarrow engine #61912
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arthurlw
suggested changes
Jul 21, 2025
| @@ -2958,7 +2958,8 @@ def to_parquet( | |||
| is expected and consistent with pandas' handling of categorical data. | |||
| To manage file size and ensure a more predictable roundtrip process, | |||
| consider using :meth:`Categorical.remove_unused_categories` on the | |||
| DataFrame before saving. | |||
| DataFrame before saving | |||
| * When using the "pyarrow" engine, `DataFrame.attrs` are stored as part of the file's metadata and restored on reading. | |||
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Thanks for the PR, but I don't think we need to necessarily document this so closing. Happy to have your contributions on other issues labeled |
Given that this is a behaviour that is rather unique to the parquet format (most other IO methods in pandas don't preserve attrs, I think?), and also something that differs between both engines, this seems worth mentioning in the docs? |
jorisvandenbossche
changed the title
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I’m fine with this if the author can get the CI green |
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This PR adds documentation to
DataFrame.to_parquetandpandas.read_parquethighlighting thatDataFrame.attrsare preserved when using the "pyarrow" engine.This behavior is already implemented in
pandas/io/parquet/pyarrow.py, but was undocumented. This PR improves discoverability for users.Notessection in both docstringsFirst-time contributor 😊