Package weka.core

Class AlgVector

java.lang.Object

weka.core.AlgVector

All Implemented Interfaces:

Serializable, Cloneable, RevisionHandler

public class AlgVector
extends Object
implements Cloneable, Serializable, RevisionHandler

Class for performing operations on an algebraic vector of floating-point values.

Version:

$Revision$

Author:

Gabi Schmidberger (gabi@cs.waikato.ac.nz)

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
AlgVector(double[] array)	Constructs a vector using a given array.
AlgVector(int n)	Constructs a vector and initializes it with default values.
AlgVector(Instance instance)	Constructs a vector using an instance.
AlgVector(Instances format, Random random)	Constructs a vector using a given data format.

Method Summary

Modifier and Type	Method	Description
AlgVector	add(AlgVector other)	Returns the sum of this vector with another.
void	changeLength(double len)	Changes the length of a vector.
Object	clone()	Creates and returns a clone of this object.
double	dotMultiply(AlgVector b)	Returns the inner (or dot) product of two vectors
Instance	getAsInstance(Instances model, Random random)	Gets the elements of the vector as an instance.
double	getElement(int index)	Returns the value of a cell in the matrix.
double[]	getElements()	Gets the elements of the vector and returns them as double array.
String	getRevision()	Returns the revision string.
static void	main(String[] args)	Main method for testing this class, can take an ARFF file as first argument.
double	norm()	Returns the norm of the vector
void	normVector()	Norms this vector to length 1.0
int	numElements()	Returns the number of elements in the vector.
void	scalarMultiply(double s)	Computes the scalar product of this vector with a scalar
void	setElement(int index, double value)	Sets an element of the matrix to the given value.
void	setElements(double[] elements)	Sets the elements of the vector to values of the given array.
AlgVector	substract(AlgVector other)	Returns the difference of this vector minus another.
String	toString()	Converts a vector to a string

Methods inherited from class java.lang.Object

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

Constructor Detail

AlgVector

public AlgVector(int n)

Constructs a vector and initializes it with default values.

Parameters:

n - the number of elements

AlgVector

public AlgVector(double[] array)

Constructs a vector using a given array.

Parameters:

array - the values of the matrix

AlgVector

public AlgVector(Instances format,
                 Random random)
          throws Exception

Constructs a vector using a given data format. The vector has an element for each numerical attribute. The other attributes (nominal, string) are ignored. Random is used to initialize the attributes.

Parameters:

format - the data format to use

random - for initializing the attributes

Throws:

Exception - if something goes wrong

AlgVector

public AlgVector(Instance instance)
          throws Exception

Constructs a vector using an instance. The vector has an element for each numerical attribute. The other attributes (nominal, string) are ignored.

Parameters:

instance - with numeric attributes, that AlgVector gets build from

Throws:

Exception - if instance doesn't have access to the data format or no numeric attributes in the data

Method Detail

clone

public Object clone()
             throws CloneNotSupportedException

Creates and returns a clone of this object.

Returns:

a clone of this instance.

Throws:

CloneNotSupportedException - if an error occurs

getElement

public final double getElement(int index)

Returns the value of a cell in the matrix.

Parameters:

index - the row's index

Returns:

the value of the cell of the vector

numElements

public final int numElements()

Returns the number of elements in the vector.

Returns:

the number of rows

setElement

public final void setElement(int index,
                             double value)

Sets an element of the matrix to the given value.

Parameters:

index - the elements index

value - the new value

setElements

public final void setElements(double[] elements)

Sets the elements of the vector to values of the given array. Performs a deep copy.

Parameters:

elements - an array of doubles

getElements

public double[] getElements()

Gets the elements of the vector and returns them as double array.

Returns:

an array of doubles

getAsInstance

public Instance getAsInstance(Instances model,
                              Random random)
                       throws Exception

Gets the elements of the vector as an instance. !! NON-numeric data is ignored sofar

Parameters:

model - the dataset structure to fit the data to

random - in case of nominal values a random label is taken

Returns:

an array of doubles

Throws:

Exception - if length of vector is not number of numerical attributes

add

public final AlgVector add(AlgVector other)

Returns the sum of this vector with another.

Parameters:

other - the vector to add

Returns:

a vector containing the sum.

substract

public final AlgVector substract(AlgVector other)

Returns the difference of this vector minus another.

Parameters:

other - the vector to subtract

Returns:

a vector containing the difference vector.

dotMultiply

public final double dotMultiply(AlgVector b)

Returns the inner (or dot) product of two vectors

Parameters:

b - the multiplication matrix

Returns:

the double representing the dot product

scalarMultiply

public final void scalarMultiply(double s)

Computes the scalar product of this vector with a scalar

Parameters:

s - the scalar

changeLength

public void changeLength(double len)

Changes the length of a vector.

Parameters:

len - the new length of the vector

norm

public double norm()

Returns the norm of the vector

Returns:

the norm of the vector

normVector

public final void normVector()

Norms this vector to length 1.0

toString

public String toString()

Converts a vector to a string

Overrides:

toString in class Object

Returns:

the converted string

getRevision

public String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision

main

public static void main(String[] args)
                 throws Exception

Main method for testing this class, can take an ARFF file as first argument.

Parameters:

args - commandline options

Throws:

Exception - if something goes wrong in testing