aggregator {Biobase} | R Documentation

## A Simple Class for Aggregators

### Description

A class of objects designed to help aggregate calculations over an iterative computation. The aggregator consists of three objects. An environment to hold the values. A function that sets up an initial value the first time an object is seen. An aggregate function that increments the value of an object seen previously.

### Details

This class is used to help aggregate different values over function calls. A very simple example is to use leave one out cross-validation for prediction. At each stage we first perform feature selection and then cross-validate. To keep track of how often each feature is selected we can use an aggregator. At the end of the cross-validation we can extract the names of the features chosen from `aggenv`.

### Creating Objects

`new('aggregator', aggenv = [environment], initfun = [function], aggfun = [function])`

### Slots

`aggenv`:
  Object of class 'environment', holds the values between iterations
`initfun`:
  Object of class 'function' specifies how to initialize the value for a name the first time it is encountered
`aggfun`:
  Object of class 'function' used to increment (or perform any other function) on a name

### Methods

`aggenv(aggregator)`:
  Used to access the environment of the aggregator
`aggfun(aggregator)`:
  Used to access the function that aggregates
`initfun(aggregator)`:
  Used to access the initializer function

### See Also

`Aggregate`

[Package Biobase version 2.2.2 Index]