edu.illinois.cs.cogcomp.lbjava.classify

Class DiscreteArrayFeature

java.lang.Object

edu.illinois.cs.cogcomp.lbjava.classify.Feature

edu.illinois.cs.cogcomp.lbjava.classify.DiscreteFeature

edu.illinois.cs.cogcomp.lbjava.classify.DiscretePrimitiveFeature

edu.illinois.cs.cogcomp.lbjava.classify.DiscreteArrayFeature

All Implemented Interfaces:

Serializable, Cloneable, Comparable

public class DiscreteArrayFeature
extends DiscretePrimitiveFeature

A discrete array feature keeps track of its index in the classifier's returned array as well as the total number of features in that array.

Author:

Nick Rizzolo

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	arrayIndex The feature's index in the returned array it is contained in.
protected int	arrayLength The size of the returned array this feature is contained in.

Fields inherited from class edu.illinois.cs.cogcomp.lbjava.classify.DiscretePrimitiveFeature

identifier, value

Fields inherited from class edu.illinois.cs.cogcomp.lbjava.classify.DiscreteFeature

BooleanValues, totalValues, valueIndex

Fields inherited from class edu.illinois.cs.cogcomp.lbjava.classify.Feature

containingPackage, generatingClassifier

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DiscreteArrayFeature() For internal use only.
	DiscreteArrayFeature(String p, String c, ByteString id, ByteString v, int i, int l) Sets the identifier, value, array index, and size of the containing array.
	DiscreteArrayFeature(String p, String c, ByteString id, ByteString v, short vi, short t, int i, int l) Sets all member variables.

Method Summary

Modifier and Type	Method and Description
boolean	classEquivalent(Feature f) Some features are functionally equivalent, differing only in the encoding of their values; this method will return true iff the class of this feature and f are different, but they differ only because they encode their values differently.
int	compareTo(Object o) Used to sort features into an order that is convenient both to page through and for the lexicon to read off disk.
boolean	equals(Object o) Two DiscreteArrayFeatures are equivalent when their containing packages, identifiers, indices, and values are equivalent.
boolean	fromArray() Determines if this feature comes from an array.
int	getArrayIndex() Returns the array index of this feature.
int	getArrayLength() Returns the length of the feature array that this feature comes from.
Feature	getFeatureKey(Lexicon lexicon, boolean training, int label) Return the feature that should be used to index this feature into a lexicon.
int	hashCode() The hash code of a DiscreteArrayFeature is the sum of the hash codes of the containing package, the identifier, the value and the array index.
void	lexRead(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessInputStream in, Lexicon lex, String p, String g, String si, ByteString bi) Reads the representation of a feature with this object's run-time type as stored by a lexicon, overwriting the data in this object.
String	lexWrite(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessOutputStream out, Lexicon lex, String c, String p, String g, String si, ByteString bi) Writes a binary representation of the feature intended for use by a lexicon, omitting redundant information when possible.
RealFeature	makeReal() Returns a RealArrayFeature whose value field is set to the strength of the current feature, and whose DiscretePrimitiveFeature.identifier field contains all the information necessary to distinguish this feature from other features.
void	read(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessInputStream in) Reads the representation of a feaeture with this object's run-time type from the given stream, overwriting the data in this object.
void	setArrayLength(int l) If this feature is an array feature, call this method to set its array length; otherwise, this method has no effect.
Feature	withStrength(double s) Returns a new feature object that's identical to this feature except its strength is given by s.
void	write(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessOutputStream out) Writes a complete binary representation of the feature.
void	write(StringBuffer buffer) Writes a string representation of this Feature to the specified buffer.

Methods inherited from class edu.illinois.cs.cogcomp.lbjava.classify.DiscretePrimitiveFeature

encode, getByteStringIdentifier, getByteStringValue, getStringIdentifier, getStringValue, hasByteStringIdentifier, isPrimitive, valueEquals, writeNameString

Methods inherited from class edu.illinois.cs.cogcomp.lbjava.classify.DiscreteFeature

conjunction, conjunctWith, getStrength, getValueIndex, isDiscrete, totalValues

Methods inherited from class edu.illinois.cs.cogcomp.lbjava.classify.Feature

childLexiconLookup, clone, compareNameStrings, conjunctWith, depth, getFeatureKey, getGeneratingClassifier, getPackage, hasStringIdentifier, isConjunctive, isReferrer, lexReadFeature, readFeature, removeFromChildLexicon, toString, toStringNoPackage, writeNoPackage

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

arrayIndex

protected int arrayIndex

The feature's index in the returned array it is contained in.

arrayLength

protected int arrayLength

The size of the returned array this feature is contained in.

Constructor Detail

DiscreteArrayFeature

protected DiscreteArrayFeature()

For internal use only.

See Also:

Feature.readFeature(ExceptionlessInputStream)

DiscreteArrayFeature

public DiscreteArrayFeature(String p,
                            String c,
                            ByteString id,
                            ByteString v,
                            int i,
                            int l)

Sets the identifier, value, array index, and size of the containing array. The value index and total allowable values, having not been specified, default to -1 and 0 respectively.

Parameters:

p - The new discrete feature's package.

c - The name of the classifier that produced this feature.

id - The new discrete feature's identifier.

v - The new discrete feature's value.

i - The index of this feature in the returned array.

l - The length of the array this feature is contained in.

DiscreteArrayFeature

public DiscreteArrayFeature(String p,
                            String c,
                            ByteString id,
                            ByteString v,
                            short vi,
                            short t,
                            int i,
                            int l)

Sets all member variables.

Parameters:

p - The new discrete feature's package.

c - The name of the classifier that produced this feature.

id - The new discrete feature's identifier.

v - The new discrete feature's value.

vi - The index corresponding to the value.

t - The total allowable values for this feature.

i - The index of this feature in the returned array.

l - The length of the array this feature is contained in.

Method Detail

getArrayIndex

public int getArrayIndex()

Returns the array index of this feature.

getArrayLength

public int getArrayLength()

Returns the length of the feature array that this feature comes from.

fromArray

public boolean fromArray()

Determines if this feature comes from an array.

Overrides:

fromArray in class Feature

Returns:

true.

setArrayLength

public void setArrayLength(int l)

If this feature is an array feature, call this method to set its array length; otherwise, this method has no effect.

Overrides:

setArrayLength in class Feature

Parameters:

l - The new length.

getFeatureKey

public Feature getFeatureKey(Lexicon lexicon,
                             boolean training,
                             int label)

Return the feature that should be used to index this feature into a lexicon. If the feature is binary, we return the feature with an empty value so that it will be mapped to the same weight whether it is active or not. If the feature can take multiple values, then simply return it as-is.

Overrides:

getFeatureKey in class DiscretePrimitiveFeature

Parameters:

lexicon - The lexicon into which this feature will be indexed.

training - Whether or not the learner is currently training.

label - The label of the example containing this feature, or -1 if we aren't doing per class feature counting.

Returns:

A feature object appropriate for use as the key of a map.

makeReal

public RealFeature makeReal()

Returns a RealArrayFeature whose value field is set to the strength of the current feature, and whose DiscretePrimitiveFeature.identifier field contains all the information necessary to distinguish this feature from other features.

Overrides:

makeReal in class DiscretePrimitiveFeature

withStrength

public Feature withStrength(double s)

Returns a new feature object that's identical to this feature except its strength is given by s.

Overrides:

withStrength in class DiscretePrimitiveFeature

Parameters:

s - The strength of the new feature.

Returns:

A new feature object as above, or null if this feature cannot take the specified strength.

hashCode

public int hashCode()

The hash code of a DiscreteArrayFeature is the sum of the hash codes of the containing package, the identifier, the value and the array index.

Overrides:

hashCode in class DiscretePrimitiveFeature

Returns:

The hash code of this Feature.

equals

public boolean equals(Object o)

Two DiscreteArrayFeatures are equivalent when their containing packages, identifiers, indices, and values are equivalent.

Overrides:

equals in class DiscretePrimitiveFeature

Parameters:

o - The object with which to compare this Feature.

Returns:

True iff the parameter is an equivalent Feature.

classEquivalent

public boolean classEquivalent(Feature f)

Some features are functionally equivalent, differing only in the encoding of their values; this method will return true iff the class of this feature and f are different, but they differ only because they encode their values differently. This method does not compare the values themselves, however.

Overrides:

classEquivalent in class DiscretePrimitiveFeature

Parameters:

f - Another feature.

Returns:

See above.

compareTo

public int compareTo(Object o)

Used to sort features into an order that is convenient both to page through and for the lexicon to read off disk.

Specified by:

compareTo in interface Comparable

Overrides:

compareTo in class DiscretePrimitiveFeature

Parameters:

o - An object to compare with.

Returns:

Integers appropriate for sorting features first by package, then by identifier, then by array index, then by value.

write

public void write(StringBuffer buffer)

Writes a string representation of this Feature to the specified buffer.

Overrides:

write in class DiscretePrimitiveFeature

Parameters:

buffer - The buffer to write to.

write

public void write(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessOutputStream out)

Writes a complete binary representation of the feature.

Overrides:

write in class DiscretePrimitiveFeature

Parameters:

out - The output stream.

read

public void read(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessInputStream in)

Reads the representation of a feaeture with this object's run-time type from the given stream, overwriting the data in this object.

Overrides:

read in class DiscretePrimitiveFeature

Parameters:

in - The input stream.

lexWrite

public String lexWrite(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessOutputStream out,
                       Lexicon lex,
                       String c,
                       String p,
                       String g,
                       String si,
                       ByteString bi)

Writes a binary representation of the feature intended for use by a lexicon, omitting redundant information when possible.

Overrides:

lexWrite in class DiscretePrimitiveFeature

Parameters:

out - The output stream.

lex - The lexicon out of which this feature is being written.

c - The fully qualified name of the assumed class. The runtime class of this feature won't be written if it's equivalent to c.

p - The assumed package string. This feature's package string won't be written if it's equivalent to p.

g - The assumed classifier name string. This feature's classifier name string won't be written if it's equivalent to g.

si - The assumed identifier as a string. If this feature has a string identifier, it won't be written if it's equivalent to si.

bi - The assumed identifier as a byte string. If this feature has a byte string identifier, it won't be written if it's equivalent to bi.

Returns:

The name of the runtime type of this feature.

lexRead

public void lexRead(edu.illinois.cs.cogcomp.core.datastructures.vectors.ExceptionlessInputStream in,
                    Lexicon lex,
                    String p,
                    String g,
                    String si,
                    ByteString bi)

Reads the representation of a feature with this object's run-time type as stored by a lexicon, overwriting the data in this object.

This method is appropriate for reading features as written by lexWrite(ExceptionlessOutputStream,Lexicon,String,String,String,String,ByteString).

Overrides:

lexRead in class DiscretePrimitiveFeature

Parameters:

in - The input stream.

lex - The lexicon we are reading in to.

p - The assumed package string. If no package name is given in the input stream, the instantiated feature is given this package.

g - The assumed classifier name string. If no classifier name is given in the input stream, the instantiated feature is given this classifier name.

si - The assumed identifier as a string. If the feature being read has a string identifier field and no identifier is given in the input stream, the feature is given this identifier.

bi - The assumed identifier as a byte string. If the feature being read has a byte string identifier field and no identifier is given in the input stream, the feature is given this identifier.