ptolemy.actor.lib.comm
Class HuffmanBasic

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.actor.lib.Transformer
                              ptolemy.actor.lib.comm.HuffmanBasic

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

Direct Known Subclasses:

HuffmanCoder, HuffmanDecoder

public class HuffmanBasic
extends Transformer

Given a probability distribution, generate the Huffman code book. The probability distribution is given by the pmf parameter. The corresponding alphabet is given by the alphabet parameter. The code book is in a format of an array of strings, each string consists of '0' and '1's. The code book is sent to the huffmanCodeBook output port.

Since:

Ptolemy II 4.1

Version:

$Id: HuffmanBasic.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Ye Zhou

See Also:

Serialized Form

Accepted Rating:

Red (cxh)

Proposed Rating:

Red (zhouye)

Nested Class Summary

static class

HuffmanBasic.Node A class that defines the node in binary tree that is used to construct the codebook of Huffman code.

Nested classes/interfaces inherited from class ptolemy.kernel.Entity

Entity.ContainedObjectsIterator

Field Summary

protected java.lang.String[]	_codeBook The huffman code book.
protected boolean	_parametersInvalid Flag that indicates if the parameters are invalid.
protected double[]	_pmf The probability mass function.
Parameter	alphabet The alphabet of the input.
TypedIOPort	huffmanCodeBook A port that produces the Huffman code book generated based on the probability mass function.
Parameter	pmf The probability mass function.

Fields inherited from class ptolemy.actor.lib.Transformer

input, output

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS

Fields inherited from interface ptolemy.actor.Executable

COMPLETED, NOT_READY, STOP_ITERATING

Constructor Summary

HuffmanBasic(CompositeEntity container, java.lang.String name)
Construct an actor with the given container and name.

Method Summary

private HuffmanBasic.Node	_findMinNode(java.util.LinkedList list) Find the node with the minimum probability value in the given linked list.
private void	_setCode(HuffmanBasic.Node node, java.lang.String[] codeBook) Set the Huffman codeword for the given node and all its children.
void	attributeChanged(Attribute attribute) If the attribute being changed is pmf, then verify all the elements are positive and their sum is 1.0.
java.lang.Object	clone(Workspace workspace) Override the base class to set type constraints.
void	fire() Generate the Huffman codebook for the given pmf, and encode the input into booleans and send them to the output port.
java.lang.String[]	generateCodeBook(double[] pmf) Generate the Huffman code book given the probability mass function.
void	initialize() Initialize the actor by resetting the _parametersInvalid to true.

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, _fireAt, _fireAt, attributeTypeChanged, clone, newPort, typeConstraintList, typeConstraints

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, postfire, prefire, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup

Methods inherited from class ptolemy.kernel.ComponentEntity

_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName

Methods inherited from class ptolemy.kernel.Entity

_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName

Methods inherited from class ptolemy.kernel.InstantiableNamedObj

_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface ptolemy.actor.Actor

createReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortList

Methods inherited from interface ptolemy.actor.Executable

isFireFunctional, isStrict, iterate, postfire, prefire, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable, wrapup

Methods inherited from interface ptolemy.kernel.util.Nameable

description, getContainer, getDisplayName, getFullName, getName, getName, setName

Methods inherited from interface ptolemy.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

Field Detail

pmf

public Parameter pmf

The probability mass function. This parameter is an array of doubles. Each element should be positive and the sum of all elements should be 1.0. The default value is {0.5, 0.5}.

alphabet

public Parameter alphabet

The alphabet of the input. This parameter is an ArrayToken. Its default value is {0, 1}.

huffmanCodeBook

public TypedIOPort huffmanCodeBook

A port that produces the Huffman code book generated based on the probability mass function. It is an array of strings.

_codeBook

protected java.lang.String[] _codeBook

The huffman code book.

_parametersInvalid

protected boolean _parametersInvalid

Flag that indicates if the parameters are invalid. If it is true, then a new code book needs to be generated.

_pmf

protected double[] _pmf

The probability mass function.

Constructor Detail

HuffmanBasic

public HuffmanBasic(CompositeEntity container,
                    java.lang.String name)
             throws NameDuplicationException,
                    IllegalActionException

Construct an actor with the given container and name. The output and trigger ports are also constructed.

Parameters:

container - The container.

name - The name of this actor.

Throws:

IllegalActionException - If the entity cannot be contained by the proposed container.

NameDuplicationException - If the container already has an actor with this name.

Method Detail

clone

public java.lang.Object clone(Workspace workspace)
                       throws java.lang.CloneNotSupportedException

Override the base class to set type constraints.

Overrides:

clone in class AtomicActor

Parameters:

workspace - The workspace for the new object.

Returns:

A new instance of ArrayElement.

Throws:

java.lang.CloneNotSupportedException - If a derived class contains an attribute that cannot be cloned.

See Also:

NamedObj.exportMoML(Writer, int, String), NamedObj.setDeferringChangeRequests(boolean)

attributeChanged

public void attributeChanged(Attribute attribute)
                      throws IllegalActionException

If the attribute being changed is pmf, then verify all the elements are positive and their sum is 1.0.

Overrides:

attributeChanged in class NamedObj

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If any element in pmf is non-positive or the sum is not 1.0.

fire

public void fire()
          throws IllegalActionException

Generate the Huffman codebook for the given pmf, and encode the input into booleans and send them to the output port.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - Not thrown in this base class.

generateCodeBook

public java.lang.String[] generateCodeBook(double[] pmf)

Generate the Huffman code book given the probability mass function.

Parameters:

pmf - The probability mass function.

Returns:

The code book, where each codeword is a string of '0' and '1'.

initialize

public void initialize()
                throws IllegalActionException

Initialize the actor by resetting the _parametersInvalid to true. Creat a linked list to store the nodes for the binary tree.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If the parent class throws it.

_findMinNode

private HuffmanBasic.Node _findMinNode(java.util.LinkedList list)

Find the node with the minimum probability value in the given linked list.

Parameters:

list - The given linked list.

Returns:

The node with the minimum probability value.

_setCode

private void _setCode(HuffmanBasic.Node node,
                      java.lang.String[] codeBook)

Set the Huffman codeword for the given node and all its children.

Parameters:

node - The given node.

codeBook - The code book to be generated.