Package weka.core.expressionlanguage.weka

Class InstancesHelper

  • All Implemented Interfaces:
    java.io.Serializable, Macro, MacroDeclarations, VariableDeclarations
    public class InstancesHelper
extends java.lang.Object
implements VariableDeclarations, Macro, MacroDeclarations
    A helper class to expose instance values and macros for instance values to a program

    Exposes instance values of the current instance (see setInstance(Instance) and setInstance(int) methods) as a1, A1 or ATT1 etc where the number is the attribute index (starting with 1).
    Furthermore exposes the class value as CLASS.

    Exposes the 'ismissing' macro which can only be applied to instance values and returns whether the value is set as missing in the current instance.

    Version:
    $Revision: 1000 $
    Author:
    Benjamin Weber ( benweber at student dot ethz dot ch )
    See Also:
    Serialized Form

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Node evaluate​(Node... params)
      Evaluates the 'ismissing' macro
      Macro getMacro​(java.lang.String name)
      Tries to fetch a macro
      Node getVariable​(java.lang.String name)
      Tries to fetch a variable of an instance value
      boolean hasMacro​(java.lang.String name)
      Whether the given macro is declared
      boolean hasVariable​(java.lang.String name)
      Returns whether the variable is declared
      boolean missingAccessed()
      Whether a missing value has been evaluated during computation.
      void setInstance​(int i)
      Sets the instance at index i of the supplied dataset to be the current instance
      void setInstance​(Instance instance)
      Sets the current instance to be the supplied instance

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • InstancesHelper

        public InstancesHelper​(Instances dataset)
        Constructs an InstancesHelper for the given dataset. Only attribute information is retained in memory.
        Parameters:
        dataset - the dataset whose attribute values should be exposed

      • InstancesHelper

        public InstancesHelper​(Instances dataset,
                       boolean retainData)
        Constructs an InstancesHelper for the given dataset.
        Parameters:
        dataset - the dataset
        retainData - true if the full dataset (rather than just the attribute information) is to be retained

    • Method Detail

      • hasMacro

        public boolean hasMacro​(java.lang.String name)
        Whether the given macro is declared
        Specified by:
        hasMacro in interface MacroDeclarations
        Parameters:
        name - name of the macro
        Returns:
        whether the given macro is declared

      • getMacro

        public Macro getMacro​(java.lang.String name)
        Tries to fetch a macro

        The same invariant of MacroDeclarations applies here too.
        Specified by:
        getMacro in interface MacroDeclarations
        Parameters:
        name - of the macro
        Returns:
        the macro

      • evaluate

        public Node evaluate​(Node... params)
              throws SemanticException
        Evaluates the 'ismissing' macro
        Specified by:
        evaluate in interface Macro
        Parameters:
        params - the arguments for the macro
        Returns:
        an AST node representing the ismissing function
        Throws:
        SemanticException

      • setInstance

        public void setInstance​(int i)
        Sets the instance at index i of the supplied dataset to be the current instance
        Parameters:
        i - the index of the instance to be set
        Throws:
        java.lang.UnsupportedOperationException - if the full dataset has not been retained in memory

      • setInstance

        public void setInstance​(Instance instance)
        Sets the current instance to be the supplied instance
        Parameters:
        instance - instance to be set as the current instance

      • missingAccessed

        public boolean missingAccessed()
        Whether a missing value has been evaluated during computation.

        Will be reset when the setInstance(int) or setInstance(Instance) method is called.
        Returns:
        whether a missing value has been evaluated during computation

      • hasVariable

        public boolean hasVariable​(java.lang.String name)
        Returns whether the variable is declared
        Specified by:
        hasVariable in interface VariableDeclarations
        Parameters:
        name - name of the variable
        Returns:
        whether it has been declared

      • getVariable

        public Node getVariable​(java.lang.String name)
        Tries to fetch a variable of an instance value

        The same invariant of VariableDeclarations applies here too.
        Specified by:
        getVariable in interface VariableDeclarations
        Parameters:
        name - name of the variable
        Returns:
        node representing the instance value