polars.Expr.list.sample#

Expr.list.sample(
n: int | IntoExprColumn | None = None,
*,
fraction: float | IntoExprColumn | None = None,
with_replacement: bool = False,
shuffle: bool = False,
seed: int | None = None,
) → Expr[source]#

Sample from this list.

Parameters:
n

Number of items to return. Cannot be used with fraction. Defaults to 1 if fraction is None.

fraction

Fraction of items to return. Cannot be used with n.

with_replacement

Allow values to be sampled more than once.

shuffle

Shuffle the order of sampled data points.

seed

Seed for the random number generator. If set to None (default), a random seed is generated for each sample operation.

Examples

>>> df = pl.DataFrame({"values": [[1, 2, 3], [4, 5]], "n": [2, 1]})
>>> df.with_columns(sample=pl.col("values").list.sample(n=pl.col("n"), seed=1))
shape: (2, 3)
┌───────────┬─────┬───────────┐
│ values    ┆ n   ┆ sample    │
│ ---       ┆ --- ┆ ---       │
│ list[i64] ┆ i64 ┆ list[i64] │
╞═══════════╪═════╪═══════════╡
│ [1, 2, 3] ┆ 2   ┆ [2, 1]    │
│ [4, 5]    ┆ 1   ┆ [5]       │
└───────────┴─────┴───────────┘