polars.Expr.shift_and_fill#
- Expr.shift_and_fill(periods: int, fill_value: int | float | bool | str | Expr | list[Any]) Self[source]#
Shift the values by a given period and fill the resulting null values.
- Parameters:
- periods
Number of places to shift (may be negative).
- fill_value
Fill None values with the result of this expression.
Examples
>>> df = pl.DataFrame({"foo": [1, 2, 3, 4]}) >>> df.select(pl.col("foo").shift_and_fill(1, "a")) shape: (4, 1) ┌─────┐ │ foo │ │ --- │ │ str │ ╞═════╡ │ a │ │ 1 │ │ 2 │ │ 3 │ └─────┘