polars.Expr.fill_null#
- Expr.fill_null(value: Any | None = None, strategy: FillNullStrategy | None = None, limit: int | None = None) Self [source]#
Fill null values using the specified value or strategy.
To interpolate over null values see interpolate.
- Parameters:
- value
Value used to fill null values.
- strategy{None, ‘forward’, ‘backward’, ‘min’, ‘max’, ‘mean’, ‘zero’, ‘one’}
Strategy used to fill null values.
- limit
Number of consecutive null values to fill when using the ‘forward’ or ‘backward’ strategy.
Examples
>>> df = pl.DataFrame( ... { ... "a": [1, 2, None], ... "b": [4, None, 6], ... } ... ) >>> df.fill_null(strategy="zero") shape: (3, 2) ┌─────┬─────┐ │ a ┆ b │ │ --- ┆ --- │ │ i64 ┆ i64 │ ╞═════╪═════╡ │ 1 ┆ 4 │ │ 2 ┆ 0 │ │ 0 ┆ 6 │ └─────┴─────┘ >>> df.fill_null(99) shape: (3, 2) ┌─────┬─────┐ │ a ┆ b │ │ --- ┆ --- │ │ i64 ┆ i64 │ ╞═════╪═════╡ │ 1 ┆ 4 │ │ 2 ┆ 99 │ │ 99 ┆ 6 │ └─────┴─────┘ >>> df.fill_null(strategy="forward") shape: (3, 2) ┌─────┬─────┐ │ a ┆ b │ │ --- ┆ --- │ │ i64 ┆ i64 │ ╞═════╪═════╡ │ 1 ┆ 4 │ │ 2 ┆ 4 │ │ 2 ┆ 6 │ └─────┴─────┘