org.rrd4j.data

Class CubicSplineInterpolator

java.lang.Object

org.rrd4j.data.Plottable

org.rrd4j.data.CubicSplineInterpolator

public class CubicSplineInterpolator
extends Plottable

Class used to interpolate datasource values from the collection of (timestamp, values) points using natural cubic spline interpolation.

WARNING: So far, this class cannot handle NaN datasource values (an exception will be thrown by the constructor). Future releases might change this.

Constructor Summary

Constructors

Constructor and Description
CubicSplineInterpolator(Calendar[] dates, double[] values) Creates cubic spline interpolator from arrays of GregorianCalendar objects and corresponding datasource values.
CubicSplineInterpolator(Date[] dates, double[] values) Creates cubic spline interpolator from arrays of Date objects and corresponding datasource values.
CubicSplineInterpolator(double[] x, double[] y) Creates cubic spline interpolator for an array of 2D-points.
CubicSplineInterpolator(long[] timestamps, double[] values) Creates cubic spline interpolator from arrays of timestamps and corresponding datasource values.

Method Summary

Methods

Modifier and Type	Method and Description
double	getValue(double xval) Calculates spline-interpolated y-value for the corresponding x-value.
double	getValue(long timestamp) Retrieves datapoint value based on a given timestamp.

Methods inherited from class java.lang.Object

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

Constructor Detail

CubicSplineInterpolator

public CubicSplineInterpolator(long[] timestamps,
                       double[] values)

Creates cubic spline interpolator from arrays of timestamps and corresponding datasource values.

Parameters:

timestamps - timestamps in seconds

values - corresponding datasource values

Throws:

IllegalArgumentException - Thrown if supplied arrays do not contain at least 3 values, or if timestamps are not ordered, or array lengths are not equal, or some datasource value is NaN.

CubicSplineInterpolator

public CubicSplineInterpolator(Date[] dates,
                       double[] values)

Creates cubic spline interpolator from arrays of Date objects and corresponding datasource values.

Parameters:

dates - Array of Date objects

values - corresponding datasource values

Throws:

IllegalArgumentException - Thrown if supplied arrays do not contain at least 3 values, or if timestamps are not ordered, or array lengths are not equal, or some datasource value is NaN.

CubicSplineInterpolator

public CubicSplineInterpolator(Calendar[] dates,
                       double[] values)

Creates cubic spline interpolator from arrays of GregorianCalendar objects and corresponding datasource values.

Parameters:

dates - Array of GregorianCalendar objects

values - corresponding datasource values

Throws:

IllegalArgumentException - Thrown if supplied arrays do not contain at least 3 values, or if timestamps are not ordered, or array lengths are not equal, or some datasource value is NaN.

CubicSplineInterpolator

public CubicSplineInterpolator(double[] x,
                       double[] y)

Creates cubic spline interpolator for an array of 2D-points.

Parameters:

x - x-axis point coordinates

y - y-axis point coordinates

Throws:

IllegalArgumentException - Thrown if supplied arrays do not contain at least 3 values, or if timestamps are not ordered, or array lengths are not equal, or some datasource value is NaN.

Method Detail

getValue

public double getValue(double xval)

Calculates spline-interpolated y-value for the corresponding x-value. Call this if you need spline-interpolated values in your code.

Parameters:

xval - x-value

Returns:

inteprolated y-value

getValue

public double getValue(long timestamp)

Retrieves datapoint value based on a given timestamp. Use this method if you only have one series of data in this class. Method overridden from the base class. This method will be called by the framework. Call this method only if you need spline-interpolated values in your code.

Overrides:

getValue in class Plottable

Parameters:

timestamp - Timestamp in seconds for the datapoint.

Returns:

Double value of the datapoint.