Method Average<TKey, TProps, TValue>(IRedbGrouping<TKey, TProps>, Expression<Func<TProps, TValue>>)

Average in a group: Agg.Average(g, x => x.Age)

public static double Average<TKey, TProps, TValue>(IRedbGrouping<TKey, TProps> group, Expression<Func<TProps, TValue>> selector) where TProps : class, new()