polars.internals.expr.ExprListNameSpace.to_struct¶
- ExprListNameSpace.to_struct(n_field_strategy: str = 'first_non_null', name_generator: Optional[Callable[[int], str]] = None) polars.internals.expr.Expr¶
Convert the series of type List to a series of type Struct.
- Parameters
- n_field_strategy
Strategy to determine the number of fields of the struct. Any of {‘first_non_null’, ‘max_width’}
- name_generator
A custom function that can be used to generate the field names. Default field names are field_0, field_1 .. field_n
Examples
>>> df = pl.DataFrame({"a": [[1, 2, 3], [1, 2]]}) >>> df.select([pl.col("a").arr.to_struct()]) shape: (2, 1) ┌────────────┐ │ a │ │ --- │ │ struct[3] │ ╞════════════╡ │ {1,2,3} │ ├╌╌╌╌╌╌╌╌╌╌╌╌┤ │ {1,2,null} │ └────────────┘ >>> df.select( ... [ ... pl.col("a").arr.to_struct( ... name_generator=lambda idx: f"col_name_{idx}" ... ) ... ] ... ).to_series().to_list() [{'col_name_0': 1, 'col_name_1': 2, 'col_name_2': 3}, {'col_name_0': 1, 'col_name_1': 2, 'col_name_2': None}]