org.carrot2.matrix.factorization
Class LocalNonnegativeMatrixFactorization

java.lang.Object
  org.carrot2.matrix.factorization.LocalNonnegativeMatrixFactorization

All Implemented Interfaces:

IIterativeMatrixFactorization, IMatrixFactorization

public class LocalNonnegativeMatrixFactorization
extends Object

Performs matrix factorization using the Local Non-negative Matrix Factorization algorithm with minimization of the Kullback-Leibler divergence between A and UV' and multiplicative updating.

Field Summary

protected org.apache.mahout.math.matrix.DoubleMatrix2D	A Input matrix
protected double[]	aggregates Sorting aggregates
protected double	approximationError Current approximation error
protected double[]	approximationErrors Approximation errors during subsequent iterations
protected static int	DEFAULT_K
protected static int	DEFAULT_MAX_ITERATIONS
protected static boolean	DEFAULT_ORDERED
protected static ISeedingStrategy	DEFAULT_SEEDING_STRATEGY
protected static double	DEFAULT_STOP_THRESHOLD
protected int	iterationsCompleted Iteration counter
protected int	k The desired number of base vectors
protected int	maxIterations The maximum number of iterations the algorithm is allowed to run
protected boolean	ordered Order base vectors according to their 'activity'?
protected ISeedingStrategy	seedingStrategy Seeding strategy
protected double	stopThreshold If the percentage decrease in approximation error becomes smaller than stopThreshold, the algorithm will stop.
protected org.apache.mahout.math.matrix.DoubleMatrix2D	U Base vector result matrix
protected org.apache.mahout.math.matrix.DoubleMatrix2D	V Coefficient result matrix

Constructor Summary

LocalNonnegativeMatrixFactorization(org.apache.mahout.math.matrix.DoubleMatrix2D A)
Creates the LocalNonnegativeMatrixFactorization object for matrix A.

Method Summary

void	compute() Computes the factorization.
double[]	getAggregates() Returns column aggregates for a sorted factorization, and null for an unsorted factorization.
double	getApproximationError() Returns final approximation error or -1 if the approximation error calculation has been turned off (see setMaxIterations(int).
double[]	getApproximationErrors() Returns an array of approximation errors during after subsequent iterations of the algorithm.
int	getIterationsCompleted() Returns the number of iterations the algorithm has completed.
int	getK() Returns the number of base vectors k .
int	getMaxIterations() Returns the maximum number of iterations the algorithm is allowed to run.
ISeedingStrategy	getSeedingStrategy() Returns current ISeedingStrategy.
double	getStopThreshold() Returns the algorithms stopThreshold.
org.apache.mahout.math.matrix.DoubleMatrix2D	getU() Returns the U matrix (base vectors matrix).
org.apache.mahout.math.matrix.DoubleMatrix2D	getV() Returns the V matrix (coefficient matrix)
boolean	isOrdered() Returns true when the factorization is set to generate an ordered basis.
protected void	order() Orders U and V matrices according to the 'activity' of base vectors.
void	setK(int k) Sets the number of base vectors k .
void	setMaxIterations(int maxIterations) Sets the maximum number of iterations the algorithm is allowed to run.
void	setOrdered(boolean ordered) Set to true to generate an ordered basis.
void	setSeedingStrategy(ISeedingStrategy seedingStrategy) Sets new ISeedingStrategy.
void	setStopThreshold(double stopThreshold) Sets the algorithms stopThreshold.
String	toString()
protected boolean	updateApproximationError()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.carrot2.matrix.factorization.IMatrixFactorization

getU, getV

Field Detail

k

protected int k

The desired number of base vectors

DEFAULT_K

protected static int DEFAULT_K

maxIterations

protected int maxIterations

The maximum number of iterations the algorithm is allowed to run

DEFAULT_MAX_ITERATIONS

protected static final int DEFAULT_MAX_ITERATIONS

See Also:

Constant Field Values

stopThreshold

protected double stopThreshold

If the percentage decrease in approximation error becomes smaller than stopThreshold, the algorithm will stop. Note: calculation of approximation error is quite costly. Setting the threshold to -1 turns off approximation error calculation and hence makes the algorithm do the maximum number of iterations.

DEFAULT_STOP_THRESHOLD

protected static double DEFAULT_STOP_THRESHOLD

seedingStrategy

protected ISeedingStrategy seedingStrategy

Seeding strategy

DEFAULT_SEEDING_STRATEGY

protected static final ISeedingStrategy DEFAULT_SEEDING_STRATEGY

ordered

protected boolean ordered

Order base vectors according to their 'activity'?

DEFAULT_ORDERED

protected static final boolean DEFAULT_ORDERED

See Also:

Constant Field Values

approximationError

protected double approximationError

Current approximation error

approximationErrors

protected double[] approximationErrors

Approximation errors during subsequent iterations

iterationsCompleted

protected int iterationsCompleted

Iteration counter

aggregates

protected double[] aggregates

Sorting aggregates

A

protected org.apache.mahout.math.matrix.DoubleMatrix2D A

Input matrix

U

protected org.apache.mahout.math.matrix.DoubleMatrix2D U

Base vector result matrix

V

protected org.apache.mahout.math.matrix.DoubleMatrix2D V

Coefficient result matrix

Constructor Detail

LocalNonnegativeMatrixFactorization

public LocalNonnegativeMatrixFactorization(org.apache.mahout.math.matrix.DoubleMatrix2D A)

Creates the LocalNonnegativeMatrixFactorization object for matrix A. Before accessing results, perform computations by calling the compute()method.

Parameters:

A - matrix to be factorized

Method Detail

compute

public void compute()

Computes the factorization.

toString

public String toString()

Overrides:

toString in class Object

setK

public void setK(int k)

Sets the number of base vectors k .

Parameters:

k - the number of base vectors

getK

public int getK()

Returns the number of base vectors k .

updateApproximationError

protected boolean updateApproximationError()

Returns:

true if the decrease in the approximation error is smaller than the stopThreshold

order

protected void order()

Orders U and V matrices according to the 'activity' of base vectors.

getSeedingStrategy

public ISeedingStrategy getSeedingStrategy()

Returns current ISeedingStrategy.

setSeedingStrategy

public void setSeedingStrategy(ISeedingStrategy seedingStrategy)

Sets new ISeedingStrategy.

getMaxIterations

public int getMaxIterations()

Returns the maximum number of iterations the algorithm is allowed to run.

setMaxIterations

public void setMaxIterations(int maxIterations)

Sets the maximum number of iterations the algorithm is allowed to run.

getStopThreshold

public double getStopThreshold()

Returns the algorithms stopThreshold. If the percentage decrease in approximation error becomes smaller than stopThreshold, the algorithm will stop.

setStopThreshold

public void setStopThreshold(double stopThreshold)

Sets the algorithms stopThreshold. If the percentage decrease in approximation error becomes smaller than stopThreshold, the algorithm will stop.

Note: calculation of approximation error is quite costly. Setting the threshold to -1 turns off calculation of the approximation error and hence makes the algorithm do the maximum allowed number of iterations.

getApproximationError

public double getApproximationError()

Returns final approximation error or -1 if the approximation error calculation has been turned off (see setMaxIterations(int).

Specified by:

getApproximationError in interface IIterativeMatrixFactorization

Returns:

final approximation error or -1

getApproximationErrors

public double[] getApproximationErrors()

Returns an array of approximation errors during after subsequent iterations of the algorithm. Element 0 of the array contains the approximation error before the first iteration. The array is null if the approximation error calculation has been turned off (see setMaxIterations(int).

getIterationsCompleted

public int getIterationsCompleted()

Description copied from interface: IIterativeMatrixFactorization

Returns the number of iterations the algorithm has completed.

Specified by:

getIterationsCompleted in interface IIterativeMatrixFactorization

Returns:

the number of iterations the algorithm has completed

isOrdered

public boolean isOrdered()

Returns true when the factorization is set to generate an ordered basis.

setOrdered

public void setOrdered(boolean ordered)

Set to true to generate an ordered basis.

getAggregates

public double[] getAggregates()

Returns column aggregates for a sorted factorization, and null for an unsorted factorization.

getU

public org.apache.mahout.math.matrix.DoubleMatrix2D getU()

Description copied from interface: IMatrixFactorization

Returns the U matrix (base vectors matrix).

Specified by:

getU in interface IMatrixFactorization

Returns:

U matrix

getV

public org.apache.mahout.math.matrix.DoubleMatrix2D getV()

Description copied from interface: IMatrixFactorization

Returns the V matrix (coefficient matrix)

Specified by:

getV in interface IMatrixFactorization

Returns:

V matrix