org.apache.commons.math3.ml.neuralnet

Class Neuron

java.lang.Object

org.apache.commons.math3.ml.neuralnet.Neuron

All Implemented Interfaces:

java.io.Serializable

public class Neuron
extends java.lang.Object
implements java.io.Serializable

Describes a neuron element of a neural network. This class aims to be thread-safe.

Since:

3.3

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	Neuron.SerializationProxy Serialization.

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.concurrent.atomic.AtomicReference<double[]>	features Neuron data.
private long	identifier Identifier.
private java.util.concurrent.atomic.AtomicLong	numberOfAttemptedUpdates Number of attempts to update a neuron.
private java.util.concurrent.atomic.AtomicLong	numberOfSuccessfulUpdates Number of successful updates of a neuron.
private static long	serialVersionUID Serializable.
private int	size Length of the feature set.

Constructor Summary

Constructors

Constructor and Description
Neuron(long identifier, double[] features) Creates a neuron.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	compareAndSetFeatures(double[] expect, double[] update) Tries to atomically update the neuron's features.
private boolean	containSameValues(double[] current, double[] expect) Checks whether the contents of both arrays is the same.
Neuron	copy() Performs a deep copy of this instance.
double[]	getFeatures() Gets the neuron's features.
long	getIdentifier() Gets the neuron's identifier.
long	getNumberOfAttemptedUpdates() Retrieves the number of calls to the compareAndSetFeatures method.
long	getNumberOfSuccessfulUpdates() Retrieves the number of successful calls to the compareAndSetFeatures method.
int	getSize() Gets the length of the feature set.
private void	readObject(java.io.ObjectInputStream in) Prevents proxy bypass.
private java.lang.Object	writeReplace() Custom serialization.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

Serializable.

See Also:

Constant Field Values

identifier

private final long identifier

Identifier.

size

private final int size

Length of the feature set.

features

private final java.util.concurrent.atomic.AtomicReference<double[]> features

Neuron data.

numberOfAttemptedUpdates

private final java.util.concurrent.atomic.AtomicLong numberOfAttemptedUpdates

Number of attempts to update a neuron.

numberOfSuccessfulUpdates

private final java.util.concurrent.atomic.AtomicLong numberOfSuccessfulUpdates

Number of successful updates of a neuron.

Constructor Detail

Neuron

Neuron(long identifier,
      double[] features)

Creates a neuron. The size of the feature set is fixed to the length of the given argument.
Constructor is package-private: Neurons must be created by the network instance to which they will belong.

Parameters:

identifier - Identifier (assigned by the Network).

features - Initial values of the feature set.

Method Detail

copy

public Neuron copy()

Performs a deep copy of this instance. Upon return, the copied and original instances will be independent: Updating one will not affect the other.

Returns:

a new instance with the same state as this instance.

Since:

3.6

getIdentifier

public long getIdentifier()

Gets the neuron's identifier.

Returns:

the identifier.

getSize

public int getSize()

Gets the length of the feature set.

Returns:

the number of features.

getFeatures

public double[] getFeatures()

Gets the neuron's features.

Returns:

a copy of the neuron's features.

compareAndSetFeatures

public boolean compareAndSetFeatures(double[] expect,
                            double[] update)

Tries to atomically update the neuron's features. Update will be performed only if the expected values match the current values.
In effect, when concurrent threads call this method, the state could be modified by one, so that it does not correspond to the the state assumed by another. Typically, a caller retrieves the current state, and uses it to compute the new state. During this computation, another thread might have done the same thing, and updated the state: If the current thread were to proceed with its own update, it would overwrite the new state (which might already have been used by yet other threads). To prevent this, the method does not perform the update when a concurrent modification has been detected, and returns false. When this happens, the caller should fetch the new current state, redo its computation, and call this method again.

Parameters:

expect - Current values of the features, as assumed by the caller. Update will never succeed if the contents of this array does not match the values returned by getFeatures().

update - Features's new values.

Returns:

true if the update was successful, false otherwise.

Throws:

DimensionMismatchException - if the length of update is not the same as specified in the constructor.

getNumberOfAttemptedUpdates

public long getNumberOfAttemptedUpdates()

Retrieves the number of calls to the compareAndSetFeatures method. Note that if the caller wants to use this method in combination with getNumberOfSuccessfulUpdates(), additional synchronization may be required to ensure consistency.

Returns:

the number of update attempts.

Since:

3.6

getNumberOfSuccessfulUpdates

public long getNumberOfSuccessfulUpdates()

Retrieves the number of successful calls to the compareAndSetFeatures method. Note that if the caller wants to use this method in combination with getNumberOfAttemptedUpdates(), additional synchronization may be required to ensure consistency.

Returns:

the number of successful updates.

Since:

3.6

containSameValues

private boolean containSameValues(double[] current,
                        double[] expect)

Checks whether the contents of both arrays is the same.

Parameters:

current - Current values.

expect - Expected values.

Returns:

true if the arrays contain the same values.

Throws:

DimensionMismatchException - if the length of expected is not the same as specified in the constructor.

readObject

private void readObject(java.io.ObjectInputStream in)

Prevents proxy bypass.

Parameters:

in - Input stream.

writeReplace

private java.lang.Object writeReplace()

Custom serialization.

Returns:

the proxy instance that will be actually serialized.