# Package cascading.operation.aggregator

Class Summary
Class | Description
--- | ---
Average | Class Average is an `Aggregator` that returns the average of all numeric values in the current group.
Average.Context | Class Context is used to hold intermediate values.
Count | Class Count is an `Aggregator` that calculates the number of items in the current group.
ExtentBase | Class ExtentBase is the base class for First and Last.
ExtremaValueBase | Class ExtremaValueBase is the base class for MaxValue and MinValue where the values are expected to by `Comparable` types and the `Comparable.compareTo(Object)` result is use for max/min comparison.
ExtremaValueBase.Context |
First | Class First is an `Aggregator` that returns the first `Tuple` encountered in a grouping.
Last | Class Last is an `Aggregator` that returns the last `Tuple` encountered.
MaxValue | Class MaxValue is an `Aggregator` that returns the maximum value encountered in the current group.
MinValue | Class Min is an `Aggregator` that returns the minimum value encountered in the current group.
Sum | Class Sum is an `Aggregator` that returns the sum of all numeric values in the current group.