Package org.rrd4j.data

Class CubicSplineInterpolator

  • All Implemented Interfaces:
    IPlottable
    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 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.
        Specified by:
        getValue in interface IPlottable
        Specified by:
        getValue in class Plottable
        Parameters:
        timestamp - Timestamp in seconds for the datapoint.
        Returns:
        Double value of the datapoint.