polars.arg_where — Polars documentation (original) (raw)

polars.arg_where(condition: Expr | Series, *, eager: bool = False) → Expr | Series[source]#

Return indices where condition evaluates True.

Parameters:

condition

Boolean expression to evaluate

eager

Evaluate immediately and return a Series; this requires that the given condition is itself a Series. If set to False (default), return an expression instead.

Examples

df = pl.DataFrame({"a": [1, 2, 3, 4, 5]}) df.select( ... [ ... pl.arg_where(pl.col("a") % 2 == 0), ... ] ... ).to_series() shape: (2,) Series: 'a' [u32] [ 1 3 ]