ai.libs.jaicore.ml.tsc.classifier.neighbors

Class NearestNeighborClassifier

java.lang.Object

ai.libs.jaicore.ml.tsc.classifier.ASimplifiedTSClassifier<java.lang.Integer>

ai.libs.jaicore.ml.tsc.classifier.neighbors.NearestNeighborClassifier

public class NearestNeighborClassifier
extends ASimplifiedTSClassifier<java.lang.Integer>

K-Nearest-Neighbor classifier for time series. Given an integer k, a distance measure d (ai.libs.jaicore.ml.tsc.distances), a training set of time series TRAIN = {(x, y)} and a test time series T (or a set of test time series).

The set of k nearest neighbors NN for T is a subset (or equal) of TRAIN with cardinality k such that for all (T, S) with S in TRAIN\NN holds d(S, T) >= max_{T' in NN} d(S, T').

From the labels of the instances in NN the label for T is aggregated, e.g. via majority vote.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NearestNeighborClassifier.VoteType Votes types that describe how to aggregate the prediciton for a test instance on its nearest neighbors found.

Field Summary

Fields

Modifier and Type	Field and Description
protected static ai.libs.jaicore.ml.tsc.classifier.neighbors.NearestNeighborClassifier.NearestNeighborComparator	nearestNeighborComparator Singleton comparator instance for the nearest neighbor priority queues, used for the nearest neighbor calculation.
protected int[]	targets Target values for the instances.
protected double[][]	timestamps Timestamp matrix containing the timestamps of the instances.
protected double[][]	values Value matrix containing the time series instances.

Fields inherited from class ai.libs.jaicore.ml.tsc.classifier.ASimplifiedTSClassifier

classMapper, trained

Constructor Summary

Constructors

Constructor and Description
NearestNeighborClassifier(int k, ITimeSeriesDistance distanceMeasure) Creates a k nearest neighbor classifier using majority vote.
NearestNeighborClassifier(int k, ITimeSeriesDistance distanceMeasure, NearestNeighborClassifier.VoteType voteType) Creates a k nearest neighbor classifier.
NearestNeighborClassifier(ITimeSeriesDistance distanceMeasure) Creates a 1 nearest neighbor classifier using majority vote.

Method Summary

Modifier and Type	Method and Description
protected java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>>	calculateNearestNeigbors(double[] testInstance) Determine the k nearest neighbors for a test instance.
protected int	calculatePrediction(double[] testInstance) Calculates predicition on a single test instance.
ITimeSeriesDistance	getDistanceMeasure() Getter for the distance measure.
int	getK() Getter for the k value, @see #k.
NearestNeighborLearningAlgorithm	getLearningAlgorithm(TimeSeriesDataset dataset)
NearestNeighborClassifier.VoteType	getVoteType() Getter for the vote type.
java.lang.Integer	predict(double[] univInstance) Predicts on univariate instance.
java.util.List<java.lang.Integer>	predict(TimeSeriesDataset dataset) Predicts on a dataset.
protected void	setTargets(int[] targets) Sets the targets.
protected void	setTimestamps(double[][] timestamps) Sets the timestamps.
protected void	setValues(double[][] values) Sets the value matrix.
protected int	vote(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors) Performs a vote on the nearest neighbors found.
protected int	voteMajority(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors) Performs a majority vote on the set nearest neighbors found.
protected int	voteWeightedProportionalToDistance(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors) Performs a vote with weights proportional to the distance on the set nearest neighbors found.
protected int	voteWeightedStepwise(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors) Performs a vote with stepwise weights 1, 2, .., k on the set nearest neighbors found.

Methods inherited from class ai.libs.jaicore.ml.tsc.classifier.ASimplifiedTSClassifier

checkWhetherPredictionIsPossible, getClassMapper, isTrained, predict, setClassMapper, train

Methods inherited from class java.lang.Object

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

Field Detail

nearestNeighborComparator

protected static final ai.libs.jaicore.ml.tsc.classifier.neighbors.NearestNeighborClassifier.NearestNeighborComparator nearestNeighborComparator

Singleton comparator instance for the nearest neighbor priority queues, used for the nearest neighbor calculation.

values

protected double[][] values

Value matrix containing the time series instances. Set by algorithm.

timestamps

protected double[][] timestamps

Timestamp matrix containing the timestamps of the instances. Set by the algorihm.

targets

protected int[] targets

Target values for the instances. Set by the algorithm.

Constructor Detail

NearestNeighborClassifier

public NearestNeighborClassifier(int k,
                                 ITimeSeriesDistance distanceMeasure,
                                 NearestNeighborClassifier.VoteType voteType)

Creates a k nearest neighbor classifier.

Parameters:

k - The number of nearest neighbors.

distanceMeasure - Distance measure for calculating the distances between every pair of train and test instances.

voteType - Vote type to use to aggregate the the classes of the the k nearest neighbors into a single class prediction.

NearestNeighborClassifier

public NearestNeighborClassifier(int k,
                                 ITimeSeriesDistance distanceMeasure)

Creates a k nearest neighbor classifier using majority vote.

Parameters:

k - The number of nearest neighbors.

distanceMeasure - Distance measure for calculating the distances between every pair of train and test instances.

NearestNeighborClassifier

public NearestNeighborClassifier(ITimeSeriesDistance distanceMeasure)

Creates a 1 nearest neighbor classifier using majority vote.

Parameters:

distanceMeasure - Distance measure for calculating the distances between every pair of train and test instances.

Method Detail

predict

public java.lang.Integer predict(double[] univInstance)
                          throws PredictionException

Predicts on univariate instance.

Specified by:

predict in class ASimplifiedTSClassifier<java.lang.Integer>

Parameters:

univInstance - The univariate instance.

Returns:

Class prediction for the instance.

Throws:

PredictionException - If something fails during the prediction process.

predict

public java.util.List<java.lang.Integer> predict(TimeSeriesDataset dataset)
                                          throws PredictionException

Predicts on a dataset.

Specified by:

predict in class ASimplifiedTSClassifier<java.lang.Integer>

Parameters:

dataset - The dataset.

Returns:

List of class predicitons for each instance of the dataset.

Throws:

PredictionException - If something fails during the prediction process

calculatePrediction

protected int calculatePrediction(double[] testInstance)

Calculates predicition on a single test instance.

Parameters:

testInstance - The test instance (not null assured within class).

Returns:

calculateNearestNeigbors

protected java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> calculateNearestNeigbors(double[] testInstance)

Determine the k nearest neighbors for a test instance.

Parameters:

testInstance - The time series to determine the k nearest neighbors for.

Returns:

Queue of the k nearest neighbors as pairs (class, distance).

vote

protected int vote(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors)

Performs a vote on the nearest neighbors found. Delegates the vote according to the vote type.

Parameters:

nearestNeighbors - Priority queue of (class, distance)-pairs for nearest neigbors, sorted by distance ascending. (Not null assured within class)

Returns:

Result of the vote, i.e. the predicted class.

voteWeightedStepwise

protected int voteWeightedStepwise(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors)

Performs a vote with stepwise weights 1, 2, .., k on the set nearest neighbors found.

Parameters:

nearestNeighbors - Priority queue of (class, distance)-pairs for nearest neigbors, sorted by distance ascending. (Not null assured within class)

Returns:

Result of the vote, i.e. the predicted class.

voteWeightedProportionalToDistance

protected int voteWeightedProportionalToDistance(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors)

Performs a vote with weights proportional to the distance on the set nearest neighbors found.

Parameters:

nearestNeighbors - Priority queue of (class, distance)-pairs for nearest neigbors, sorted by distance ascending. (Not null assured within class)

Returns:

Result of the vote, i.e. the predicted class.

voteMajority

protected int voteMajority(java.util.PriorityQueue<ai.libs.jaicore.basic.sets.Pair<java.lang.Integer,java.lang.Double>> nearestNeighbors)

Performs a majority vote on the set nearest neighbors found.

Parameters:

nearestNeighbors - Priority queue of (class, distance)-pairs for nearest neigbors, sorted by distance ascending. (Not null assured within class)

Returns:

Result of the vote, i.e. the predicted class.

setValues

protected void setValues(double[][] values)

Sets the value matrix.

Parameters:

values -

setTimestamps

protected void setTimestamps(double[][] timestamps)

Sets the timestamps.

Parameters:

timestamps -

setTargets

protected void setTargets(int[] targets)

Sets the targets.

Parameters:

targets -

getK

public int getK()

Getter for the k value, @see #k.

Returns:

k

getVoteType

public NearestNeighborClassifier.VoteType getVoteType()

Getter for the vote type. @see #voteType.

Returns:

The vote type.

getDistanceMeasure

public ITimeSeriesDistance getDistanceMeasure()

Getter for the distance measure. @see #distanceMeasure.

Returns:

getLearningAlgorithm

public NearestNeighborLearningAlgorithm getLearningAlgorithm(TimeSeriesDataset dataset)

Specified by:

getLearningAlgorithm in class ASimplifiedTSClassifier<java.lang.Integer>