narwhals.Series.list

contains

contains(item: NonNestedLiteral) -> SeriesT

Check if sublists contain the given item.

Parameters:

Name	Type	Description	Default
item	NonNestedLiteral	Item that will be checked for membership.	required

Returns:

Type	Description
SeriesT	A new expression.

Examples:

>>> import polars as pl
>>> import narwhals as nw
>>> s_native = pl.Series([[1, 2], None, []])
>>> s = nw.from_native(s_native, series_only=True)
>>> s.list.contains(1).to_native()
shape: (3,)
Series: '' [bool]
[
        true
        null
        false
]

len

len() -> SeriesT

Return the number of elements in each list.

Null values count towards the total.

Returns:

Type	Description
SeriesT	A new series.

Examples:

>>> import pyarrow as pa
>>> import narwhals as nw
>>> s_native = pa.chunked_array([[[1, 2], [3, 4, None], None, []]])
>>> s = nw.from_native(s_native, series_only=True)
>>> s.list.len().to_native()
<pyarrow.lib.ChunkedArray object at ...>
[
  [
    2,
    3,
    null,
    0
  ]
]

unique

unique() -> SeriesT

Get the unique/distinct values in the list.

Null values are included in the result. The order of unique values is not guaranteed.

Returns:

Type	Description
SeriesT	A new series.

Examples:

>>> import polars as pl
>>> import narwhals as nw
>>> s_native = pl.Series([[1, 1, 2], [3, 3, None], None, []])
>>> s = nw.from_native(s_native, series_only=True)
>>> s.list.unique().to_native()
shape: (4,)
Series: '' [list[i64]]
[
   [1, 2]
   [null, 3]
   null
   []
]