polars_lazy::dsl

Function reduce_exprs

Source
pub fn reduce_exprs<F, E>(f: F, exprs: E) -> Expr
where F: 'static + Fn(Column, Column) -> Result<Option<Column>, PolarsError> + Send + Sync, E: AsRef<[Expr]>,
Expand description

Analogous to Iterator::reduce.

An accumulator is initialized to the series given by the first expression in exprs, and then each subsequent value of the accumulator is computed from f(acc, next_expr_series). If exprs is empty, an error is returned when collect is called.