polars.Expr.list.filter

Expr.list.filter(predicate: Expr) → Expr

Filter elements in each list by a boolean expression.

Parameters:

predicate

A boolean expression that is evaluated per list element. You can refer to the current element with pl.element().

Examples

>>> import polars as pl
>>> df = pl.DataFrame({"a": [1, 8, 3], "b": [4, 5, 2]})
>>> df.with_columns(
...     evens=pl.concat_list("a", "b").list.filter(pl.element() % 2 == 0)
... )
shape: (3, 3)
┌─────┬─────┬───────────┐
│ a   ┆ b   ┆ evens     │
│ --- ┆ --- ┆ ---       │
│ i64 ┆ i64 ┆ list[i64] │
╞═════╪═════╪═══════════╡
│ 1   ┆ 4   ┆ [4]       │
│ 8   ┆ 5   ┆ [8]       │
│ 3   ┆ 2   ┆ [2]       │
└─────┴─────┴───────────┘