dfr arg-true for dataframe

Returns indexes where values are true.

Signature

> dfr arg-true

Examples

Returns indexes where values are true

> [false true false] | dfr into-df | dfr arg-true
╭───┬──────────╮
│ # │ arg_true │
├───┼──────────┤
│ 0 │        1 │
╰───┴──────────╯