polars.io.parquet.ParquetFieldOverwrites#

Write-option overwrites for individual Parquet fields.

Warning

This functionality is considered unstable. It may be changed at any point without it being considered a breaking change.

Examples

>>> lf = pl.LazyFrame(
...     {
...         "a": [None, 2, 3, 4],
...         "b": [[1, 2, 3], [42], [13], [37]],
...         "c": [
...             {"x": "a", "y": 42},
...             {"x": "b", "y": 13},
...             {"x": "X", "y": 37},
...             {"x": "Y", "y": 15},
...         ],
...     }
... )  
>>> lf.sink_parquet(
...     "./out/parquet",
...     field_overwrites={
...         "a": ParquetFieldOverwrites(metadata={"flat_from_polars": "yes"}),
...         "b": ParquetFieldOverwrites(
...             children=ParquetFieldOverwrites(metadata={"listitem": "yes"}),
...             metadata={"list": "true"},
...         ),
...         "c": ParquetFieldOverwrites(
...             children=[
...                 ParquetFieldOverwrites(name="x", metadata={"md": "yes"}),
...                 ParquetFieldOverwrites(name="y", metadata={"md2": "Yes!"}),
...             ],
...             metadata={"struct": "true"},
...         ),
...     },
... )  

__init__( *, name: str | None = None, children: None | ParquetFieldOverwrites | Sequence[ParquetFieldOverwrites] | Mapping[str, ParquetFieldOverwrites] = None, field_id: int | None = None, metadata: Mapping[str, None | str] | None = None, required: bool | None = None, ) → None[source]#

Methods

__init__(*[, name, children, field_id, ...])

Attributes

`field_id`	The field ID used in the Parquet schema
`required`	Is the field not allowed to have missing values
`name`	Name of the column or field
`children`	Children of the column or field.
`metadata`	Arrow metadata added to the field before writing