Function polars::prelude::map_list_mul

pub fn map_list_mul<F, E>(
    function: F, 
    expr: E, 
    output_type: NoEq<Arc<dyn FunctionOutputField + 'static>>
) -> Expr where
    F: 'static + Fn(&mut [Series]) -> Result<Series, PolarsError> + Send + Sync,
    E: AsRef<[Expr]>, 

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

This function is very similar to [apply_mul], but differs in how it handles aggregations.

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