Basics

Operators

Predicates

Aggregators

Variance

Variance

Signature

variance(expr: AttrName|(Tuple->Numeric)) -> Aggregator

Examples

variance(:qty)

variance{|t| t.qty * t.price }

variance(->(t){ t.qty * t.price })

Description

Computes how far the set of input values is spread out.

Implementation notes

This aggregate function should only be used with numeric types. As of current Alf version, it does not aggregate empty sets correctly on non-numeric data types.