polars.Expr.meta.serialize#

Expr.meta.serialize(
file: IOBase | str | Path | None = None,
*,
format: SerializationFormat = 'binary',
) → bytes | str | None[source]#

Serialize this expression to a file or string in JSON format.

Parameters:
file

File path to which the result should be written. If set to None (default), the output is returned as a string instead.

format

The format in which to serialize. Options:

  • "binary": Serialize to binary format (bytes). This is the default.

  • "json": Serialize to JSON format (string).

See also

Expr.deserialize

Notes

Serialization is not stable across Polars versions: a LazyFrame serialized in one Polars version may not be deserializable in another Polars version.

Examples

Serialize the expression into a binary representation.

>>> expr = pl.col("foo").sum().over("bar")
>>> bytes = expr.meta.serialize()
>>> bytes  
b'\xa1fWindow\xa4hfunction\xa1cAgg\xa1cSum\xa1fColumncfoolpartition_by\x81...'

The bytes can later be deserialized back into an Expr object.

>>> import io
>>> pl.Expr.deserialize(io.BytesIO(bytes))  
<Expr ['col("foo").sum().over([col("ba…'] at ...>
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