weka.core
Class BinarySparseInstance

java.lang.Object
  weka.core.Instance
      weka.core.SparseInstance
          weka.core.BinarySparseInstance

All Implemented Interfaces:

Copyable, java.io.Serializable

public class BinarySparseInstance

extends SparseInstance

Class for storing a binary-data-only instance as a sparse vector. A sparse instance only requires storage for those attribute values that are non-zero. Since the objective is to reduce storage requirements for datasets with large numbers of default values, this also includes nominal attributes -- the first nominal value (i.e. that which has index 0) will not require explicit storage, so rearrange your nominal attribute value orderings if necessary. Missing values are not supported, and will be treated as 1 (true).

See Also:

Serialized Form

Field Summary

Fields inherited from class weka.core.SparseInstance

m_Indices, m_NumAttributes

Fields inherited from class weka.core.Instance

m_AttValues, m_Dataset, m_Weight, MISSING_VALUE

Constructor Summary

BinarySparseInstance(double weight, double[] attValues)
Constructor that generates a sparse instance from the given parameters.

BinarySparseInstance(double weight, int[] indices, int maxNumValues)
Constructor that inititalizes instance variable with given values.

BinarySparseInstance(Instance instance)
Constructor that generates a sparse instance from the given instance.

BinarySparseInstance(int numAttributes)
Constructor of an instance that sets weight to one, all values to 1, and the reference to the dataset to null.

BinarySparseInstance(SparseInstance instance)
Constructor that copies the info from the given instance.

Method Summary

java.lang.Object	copy() Produces a shallow copy of this instance.
(package private) void	forceDeleteAttributeAt(int position) Deletes an attribute at the given position (0 to numAttributes() - 1).
(package private) void	forceInsertAttributeAt(int position) Inserts an attribute at the given position (0 to numAttributes()) and sets its value to 1.
static void	main(java.lang.String[] options) Main method for testing this class.
Instance	mergeInstance(Instance inst) Merges this instance with the given instance and returns the result.
void	replaceMissingValues(double[] array) Does nothing, since we don't support missing values.
void	setValue(int attIndex, double value) Sets a specific value in the instance to the given value (internal floating-point format).
void	setValueSparse(int indexOfIndex, double value) Sets a specific value in the instance to the given value (internal floating-point format).
double[]	toDoubleArray() Returns the values of each attribute as an array of doubles.
java.lang.String	toString() Returns the description of one instance in sparse format.
double	value(int attIndex) Returns an instance's attribute value in internal format.
double	valueSparse(int indexOfIndex) Returns an instance's attribute value in internal format.

Methods inherited from class weka.core.SparseInstance

attributeSparse, index, isMissing, locateIndex, numAttributes, numValues

Methods inherited from class weka.core.Instance

attribute, classAttribute, classIndex, classIsMissing, classValue, dataset, deleteAttributeAt, enumerateAttributes, equalHeaders, insertAttributeAt, isMissing, isMissingSparse, isMissingValue, missingValue, numClasses, setClassMissing, setClassValue, setClassValue, setDataset, setMissing, setMissing, setValue, setValue, setValue, setWeight, stringValue, stringValue, toString, toString, value, weight

Methods inherited from class java.lang.Object

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

Constructor Detail

BinarySparseInstance

public BinarySparseInstance(Instance instance)

Constructor that generates a sparse instance from the given instance. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)

Parameters:

instance - the instance from which the attribute values and the weight are to be copied

BinarySparseInstance

public BinarySparseInstance(SparseInstance instance)

Constructor that copies the info from the given instance. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)

Parameters:

instance - the instance from which the attribute info is to be copied

BinarySparseInstance

public BinarySparseInstance(double weight,
                            double[] attValues)

Constructor that generates a sparse instance from the given parameters. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)

Parameters:

weight - the instance's weight

attValues - a vector of attribute values

BinarySparseInstance

public BinarySparseInstance(double weight,
                            int[] indices,
                            int maxNumValues)

Constructor that inititalizes instance variable with given values. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)

Parameters:

weight - the instance's weight

indices - the indices of the given values in the full vector

maxNumValues - the maximium number of values that can be stored

BinarySparseInstance

public BinarySparseInstance(int numAttributes)

Constructor of an instance that sets weight to one, all values to 1, and the reference to the dataset to null. (ie. the instance doesn't have access to information about the attribute types)

Parameters:

numAttributes - the size of the instance

Method Detail

copy

public java.lang.Object copy()

Produces a shallow copy of this instance. The copy doesn't have access to a dataset.

Specified by:

copy in interface Copyable

Overrides:

copy in class SparseInstance

Returns:

the shallow copy

mergeInstance

public Instance mergeInstance(Instance inst)

Merges this instance with the given instance and returns the result. Dataset is set to null.

Overrides:

mergeInstance in class SparseInstance

Parameters:

inst - the instance to be merged with this one

Returns:

the merged instances

replaceMissingValues

public void replaceMissingValues(double[] array)

Does nothing, since we don't support missing values.

Overrides:

replaceMissingValues in class SparseInstance

Parameters:

array - containing the means and modes

Throws:

java.lang.IllegalArgumentException - if numbers of attributes are unequal

setValue

public void setValue(int attIndex,
                     double value)

Sets a specific value in the instance to the given value (internal floating-point format). Performs a deep copy of the vector of attribute values before the value is set.

Overrides:

setValue in class SparseInstance

Parameters:

attIndex - the attribute's index

value - the new attribute value (If the corresponding attribute is nominal (or a string) then this is the new value's index as a double).

setValueSparse

public void setValueSparse(int indexOfIndex,
                           double value)

Sets a specific value in the instance to the given value (internal floating-point format). Performs a deep copy of the vector of attribute values before the value is set.

Overrides:

setValueSparse in class SparseInstance

Parameters:

indexOfIndex - the index of the attribute's index

value - the new attribute value (If the corresponding attribute is nominal (or a string) then this is the new value's index as a double).

toDoubleArray

public double[] toDoubleArray()

Returns the values of each attribute as an array of doubles.

Overrides:

toDoubleArray in class SparseInstance

Returns:

an array containing all the instance attribute values

toString

public java.lang.String toString()

Returns the description of one instance in sparse format. If the instance doesn't have access to a dataset, it returns the internal floating-point values. Quotes string values that contain whitespace characters.

Overrides:

toString in class SparseInstance

Returns:

the instance's description as a string

value

public double value(int attIndex)

Returns an instance's attribute value in internal format.

Overrides:

value in class SparseInstance

Parameters:

attIndex - the attribute's index

Returns:

the specified value as a double (If the corresponding attribute is nominal (or a string) then it returns the value's index as a double).

valueSparse

public final double valueSparse(int indexOfIndex)

Returns an instance's attribute value in internal format. Does exactly the same thing as value() if applied to an Instance.

Overrides:

valueSparse in class Instance

Parameters:

indexOfIndex - the index of the attribute's index

Returns:

the specified value as a double (If the corresponding attribute is nominal (or a string) then it returns the value's index as a double).

forceDeleteAttributeAt

void forceDeleteAttributeAt(int position)

Deletes an attribute at the given position (0 to numAttributes() - 1).

Overrides:

forceDeleteAttributeAt in class SparseInstance

forceInsertAttributeAt

void forceInsertAttributeAt(int position)

Inserts an attribute at the given position (0 to numAttributes()) and sets its value to 1.

Overrides:

forceInsertAttributeAt in class SparseInstance

main

public static void main(java.lang.String[] options)

Main method for testing this class.