polars.Expr.arr.get#

Expr.arr.get(index: int | IntoExprColumn, *, null_on_oob: bool = True) → Expr[source]#

Get the value by index in the sub-arrays.

So index 0 would return the first item of every sublist and index -1 would return the last item of every sublist if an index is out of bounds, it will return a None.

Parameters:

index: Index to return per sub-array
null_on_oob: Behavior if an index is out of bounds: True -> set as null False -> raise an error

Examples

>>> df = pl.DataFrame(
...     {"arr": [[1, 2, 3], [4, 5, 6], [7, 8, 9]], "idx": [1, -2, 0]},
...     schema={"arr": pl.Array(pl.Int32, 3), "idx": pl.Int32},
... )
>>> df.with_columns(get=pl.col("arr").arr.get("idx", null_on_oob=True))
shape: (3, 3)
┌───────────────┬─────┬─────┐
│ arr           ┆ idx ┆ get │
│ ---           ┆ --- ┆ --- │
│ array[i32, 3] ┆ i32 ┆ i32 │
╞═══════════════╪═════╪═════╡
│ [1, 2, 3]     ┆ 1   ┆ 2   │
│ [4, 5, 6]     ┆ -2  ┆ 5   │
│ [7, 8, 9]     ┆ 0   ┆ 7   │
└───────────────┴─────┴─────┘