ai.libs.jaicore.ml.tsc.features

Class TimeSeriesFeature

java.lang.Object

ai.libs.jaicore.ml.tsc.features.TimeSeriesFeature

public class TimeSeriesFeature
extends java.lang.Object

Class calculating features (e. g. mean, stddev or slope) on given subsequences of time series. Used e. g. for TimeSeriesTreeClassifier classifier.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TimeSeriesFeature.FeatureType Feature types used within the time series tree.

Field Summary

Fields

Modifier and Type	Field and Description
static int	NUM_FEATURE_TYPES Number of features used within the time series tree.

Constructor Summary

Constructors

Constructor and Description
TimeSeriesFeature()

Method Summary

Modifier and Type	Method and Description
static double	calculateFeature(TimeSeriesFeature.FeatureType fType, double[] vector, int t1, int t2, boolean useBiasCorrection) Function calculating the feature specified by the feature type fType for a given instance vector of the interval [t1, t2].
static double[]	getFeatures(double[] vector, int t1, int t2, boolean useBiasCorrection) Function calculating all features occurring in TimeSeriesFeature.FeatureType at once using an online calculation approach for mean, standard deviation and the slope.

Methods inherited from class java.lang.Object

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

Field Detail

NUM_FEATURE_TYPES

public static final int NUM_FEATURE_TYPES

Number of features used within the time series tree.

Constructor Detail

TimeSeriesFeature

public TimeSeriesFeature()

Method Detail

getFeatures

public static double[] getFeatures(double[] vector,
                                   int t1,
                                   int t2,
                                   boolean useBiasCorrection)

Function calculating all features occurring in TimeSeriesFeature.FeatureType at once using an online calculation approach for mean, standard deviation and the slope.

Parameters:

vector - The instance's vector which is used to calculate the features

t1 - Start of the interval

t2 - End of the interval (inclusive)

useBiasCorrection - Indicator whether the bias (Bessel's) correction should be used for the standard deviation calculation

Returns:

Returns an double array of the size TimeSeriesTreeLearningAlgorithm#NUM_FEATURE_TYPES storing the generated feature values.

calculateFeature

public static double calculateFeature(TimeSeriesFeature.FeatureType fType,
                                      double[] vector,
                                      int t1,
                                      int t2,
                                      boolean useBiasCorrection)

Function calculating the feature specified by the feature type fType for a given instance vector of the interval [t1, t2].

Parameters:

fType - The feature type to be calculated

instance - The instance's vector which values are used

t1 - Start of the interval

t2 - End of the interval (inclusive)

useBiasCorrection - Indicator whether the bias (Bessel's) correction should be used for the standard deviation calculation

Returns:

Returns the calculated feature for the specific instance and interval