Package uk.ac.starlink.ttools.plot2

Class HistoRanger

  • All Implemented Interfaces:
    Ranger
    public class HistoRanger
extends java.lang.Object
implements Ranger
    Histogram-capable Ranger implementation. Evenly sampled values from the input data stream are stored so that scaling based on the detailed distribution of the data, rather than just its minimum and maximum values, can be achieved.

    This ranger is not intended to calculate arithmetically accurate quantile values, but it's hopefully good enough to come up with colour maps. The current implementation does a reasonable job of adaptive sampling, but for large datasets (greater than the storage capacity) it may be biassed, especially the add(uk.ac.starlink.ttools.plot2.Ranger) method required for range calculation in parallel.

    Since:
    21 Mar 2019
    Author:
    Mark Taylor

    • Constructor Summary

      Constructors 
      Constructor Description
      HistoRanger​(int nStore, int nQuantile)
      Constructor.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void add​(Ranger other)
      Merges the contents of the supplied ranger into this one.
      static boolean canScaleHistograms​(Span span)
      Indicates whether a given span can be used to scale histograms.
      Ranger createCompatibleRanger()
      Returns a Ranger instance that is compatible with this one.
      Span createSpan()
      Returns an object characterising the range of data submitted so far.
      void submitDatum​(double d)
      Accepts a data value.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • HistoRanger

        public HistoRanger​(int nStore,
                   int nQuantile)
        Constructor. The number of samples collected and the number of quantiles can both be configured. The sample count defines the memory footprint of this object, which ought to be short lived, while the quantile count defines the memory footprint of any span objects created, which may be long-lived.
        Parameters:
        nStore - maximum number of samples to store
        nQuantile - maximum number of quantiles on which to base scaling

    • Method Detail

      • submitDatum

        public void submitDatum​(double d)
        Description copied from interface: Ranger
        Accepts a data value.
        Specified by:
        submitDatum in interface Ranger
        Parameters:
        d - datum

      • add

        public void add​(Ranger other)
        Description copied from interface: Ranger
        Merges the contents of the supplied ranger into this one. The effect is as if all the results accumulated into other had been accumulated into this one. The effect on the supplied other is undefined.

        The supplied ranger is assumed to be compatible with this one, which probably means created in the same way. If not, some RuntimeException such as a ClassCastException may result.

        Specified by:
        add in interface Ranger
        Parameters:
        other - compatible ranger instance

      • createSpan

        public Span createSpan()
        Description copied from interface: Ranger
        Returns an object characterising the range of data submitted so far. This should not be called while another thread might be calling Ranger.submitDatum(double).
        Specified by:
        createSpan in interface Ranger
        Returns:
        span of accumulated data