aggregator              package: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'

