polars_plan::dsl

Function map_list_multiple

Source
pub fn map_list_multiple<F, E>(
    function: F,
    expr: E,
    output_type: GetOutput,
) -> Expr
where F: Fn(&mut [Column]) -> PolarsResult<Option<Column>> + 'static + Send + Sync, E: AsRef<[Expr]>,
Expand description

Apply a function/closure over multiple columns once the logical plan get executed.

This function is very similar to apply_multiple, but differs in how it handles aggregations.

  • map_multiple should be used for operations that are independent of groups, e.g. multiply * 2, or raise to the power
  • apply_multiple should be used for operations that work on a group of data. e.g. sum, count, etc.
  • map_list_multiple should be used when the function expects a list aggregated series.