polars.Expr.arg_true#
- Expr.arg_true() Expr [source]#
Return indices where expression evaluates
True
.Warning
Modifies number of rows returned, so will fail in combination with other expressions. Use as only expression in
select
/with_columns
.See also
Series.arg_true
Return indices where Series is True
polars.arg_where
Examples
>>> df = pl.DataFrame({"a": [1, 1, 2, 1]}) >>> df.select((pl.col("a") == 1).arg_true()) shape: (3, 1) ┌─────┐ │ a │ │ --- │ │ u32 │ ╞═════╡ │ 0 │ │ 1 │ │ 3 │ └─────┘