polars.Series.arr.to_struct#

Series.arr.to_struct( fields: Callable[[int], str] | Sequence[str] | None = None, ) → Series[source]#

Convert the series of type Array to a series of type Struct.

Parameters:

fields: If the name and number of the desired fields is known in advance a list of field names can be given, which will be assigned by index. Otherwise, to dynamically assign field names, a custom function can be used; if neither are set, fields will be field_0, field_1 .. field_n.

Examples

Convert array to struct with default field name assignment:

>>> s1 = pl.Series("n", [[0, 1, 2], [3, 4, 5]], dtype=pl.Array(pl.Int8, 3))
>>> s2 = s1.arr.to_struct()
>>> s2
shape: (2,)
Series: 'n' [struct[3]]
[
    {0,1,2}
    {3,4,5}
]
>>> s2.struct.fields
['field_0', 'field_1', 'field_2']

Convert array to struct with field name assignment by function/index:

>>> s3 = s1.arr.to_struct(fields=lambda idx: f"n{idx:02}")
>>> s3.struct.fields
['n00', 'n01', 'n02']

Convert array to struct with field name assignment by index from a list of names:

>>> s1.arr.to_struct(fields=["one", "two", "three"]).struct.unnest()
shape: (2, 3)
┌─────┬─────┬───────┐
│ one ┆ two ┆ three │
│ --- ┆ --- ┆ ---   │
│ i8  ┆ i8  ┆ i8    │
╞═════╪═════╪═══════╡
│ 0   ┆ 1   ┆ 2     │
│ 3   ┆ 4   ┆ 5     │
└─────┴─────┴───────┘