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

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

double	getValue(double xval) Calculates spline-interpolated y-value for the corresponding x-value.
double	getValue(long timestamp) Method overridden from the base class.

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)

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

Returns:

inteprolated datasource value