Class Combiner

java.lang.Object
uk.ac.starlink.ttools.plot2.layer.Combiner
Direct Known Subclasses:
QuantileCombiner
@Equality public abstract class Combiner extends Object
Defines the combination mode for accumulating values into a bin.

Instances of this class can produce Container and BinList objects into which values can be accumulated. Once populated, those objects can be interrogated to find combined values. Note that in general those accumulated results should be multiplied by the result of calling Combiner.Type.getBinFactor(double) before use.

Note that the SUM mode is usually sensible for unweighted values, but if the values are weighted it may be more revealing to use one of the others (like MEAN).

Since:
20 Sep 2015
Author:
Mark Taylor

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static interface 
    Combiner.Container
    Defines an object that can be used to accumulate values and retrieve a result.
    static enum 
    Combiner.Type
    Defines the scaling properties of a combiner.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final Combiner
    COUNT
    Calculate the number of submitted values.
    static final Combiner
    DENSITY
    Calculate the density of all submitted values.
    static final Combiner
    HIT
    Return 1 if any value submitted, 0 otherwise.
    static final Combiner
    MAX
    Calculate the maximum of all submitted values.
    static final Combiner
    MEAN
    Calculate the mean of all submitted values.
    static final Combiner
    MEDIAN
    Calculate the median of all submitted values (slow).
    static final Combiner
    MIN
    Calculate the minimum of all submitted values.
    static final Combiner
    POP_STDEV
    Calculate the population standard deviation of all submitted values.
    static final Combiner
    Q01
    Calculate the 1st percentile of all submitted values (slow).
    static final Combiner
    Q1
    Calculate the first quartile of all submitted values (slow).
    static final Combiner
    Q3
    Calculate the third quartile of all submitted values (slow).
    static final Combiner
    Q99
    Calculate the 99th percentile of all submitted values (slow).
    static final Combiner
    SAMPLE_STDEV
    Calculate the sample standard deviation of all submitted values.
    static final Combiner
    SUM
    Calculate the sum of all submitted values.
    static final Combiner
    WEIGHTED_DENSITY
    Calculate the weighted density of all submitted values.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    Combiner(String name, String description, Combiner.Type type, boolean hasBigBin)
    Constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    abstract ArrayBinList
    createArrayBinList(int size)
    May be able to create a bin list suitable for non-sparse, moderate-sized index ranges.
    abstract uk.ac.starlink.table.ValueInfo
    createCombinedInfo(uk.ac.starlink.table.ValueInfo info, Unit scaleUnit)
    Returns a metadata object that describes the result of applying this combiner to data described by a given metadata object.
    abstract Combiner.Container
    createContainer()
    Creates an object which can be used to accumulate values.
    static Combiner
    createQuantileCombiner(String name, String descrip, double quantile)
    Creates a combiner that calculates a given quantile.
    String
    getDescription()
    Returns a short textual description of this combiner.
    static Combiner[]
    getKnownCombiners()
    Returns a list of the known general purpose instances of this class.
    String
    getName()
    Returns this combiner's name.
    Combiner.Type
    getType()
    Indicates the aggregation type.
    boolean
    hasBigBin()
    Indicates whether the bin objects used by this combiner are large.
    String
    toString()
     

    Methods inherited from class Object

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

  • Field Details

    • COUNT

      public static final Combiner COUNT
      Calculate the number of submitted values.

    • DENSITY

      public static final Combiner DENSITY
      Calculate the density of all submitted values.

    • SUM

      public static final Combiner SUM
      Calculate the sum of all submitted values.

    • WEIGHTED_DENSITY

      public static final Combiner WEIGHTED_DENSITY
      Calculate the weighted density of all submitted values.

    • MEAN

      public static final Combiner MEAN
      Calculate the mean of all submitted values.

    • MEDIAN

      public static final Combiner MEDIAN
      Calculate the median of all submitted values (slow).

    • Q1

      public static final Combiner Q1
      Calculate the first quartile of all submitted values (slow).

    • Q3

      public static final Combiner Q3
      Calculate the third quartile of all submitted values (slow).

    • SAMPLE_STDEV

      public static final Combiner SAMPLE_STDEV
      Calculate the sample standard deviation of all submitted values.

    • POP_STDEV

      public static final Combiner POP_STDEV
      Calculate the population standard deviation of all submitted values.

    • MIN

      public static final Combiner MIN
      Calculate the minimum of all submitted values.

    • MAX

      public static final Combiner MAX
      Calculate the maximum of all submitted values.

    • HIT

      public static final Combiner HIT
      Return 1 if any value submitted, 0 otherwise.

    • Q01

      public static final Combiner Q01
      Calculate the 1st percentile of all submitted values (slow).

    • Q99

      public static final Combiner Q99
      Calculate the 99th percentile of all submitted values (slow).

  • Constructor Details

    • Combiner

      protected Combiner(String name, String description, Combiner.Type type, boolean hasBigBin)
      Constructor.
      Parameters:
      name - name
      description - short textual description
      type - defines the kind of aggregation performed; note the implementation of this class does not use this value to affect the bin results calculated by this combiner, but users of this class should make use of it to interpret the bin results
      hasBigBin - indicates whether the bins used by this combiner are large (take more memory than a double)

  • Method Details

    • createContainer

      public abstract Combiner.Container createContainer()
      Creates an object which can be used to accumulate values.

      Note: Since many container instances may by generated (when using a HashBinList) it is desirable to keep the returned objects as small as possible. In particular, it's a good idea to make the returned objects instances of a static class, to avoid an unncecessary reference to the owner object, unless there's a really compelling reason to do otherwise.

      Returns:
      new container

    • createArrayBinList

      public abstract ArrayBinList createArrayBinList(int size)
      May be able to create a bin list suitable for non-sparse, moderate-sized index ranges. If a combiner implementation is able to provide an ArrayBinList implementation that should be significantly more efficient than a HashBinList, this method should return it. If not, it can return null.
      Parameters:
      size - index range of required bin list
      Returns:
      array-based bin list, or null

    • getName

      public String getName()
      Returns this combiner's name.
      Returns:
      name

    • getDescription

      public String getDescription()
      Returns a short textual description of this combiner.
      Returns:
      short description

    • getType

      public Combiner.Type getType()
      Indicates the aggregation type. This value should be used to make sense of the output bin list results.
      Returns:
      aggregation type

    • hasBigBin

      public boolean hasBigBin()
      Indicates whether the bin objects used by this combiner are large. Large means, roughly, take more memory than a double. This flag may be used to decide whether to compact bin list results.
      Returns:
      true if this combiner uses big bins

    • createCombinedInfo

      public abstract uk.ac.starlink.table.ValueInfo createCombinedInfo(uk.ac.starlink.table.ValueInfo info, Unit scaleUnit)
      Returns a metadata object that describes the result of applying this combiner to data described by a given metadata object.
      Parameters:
      info - metadata for values to be combined, usually numeric; may be null if metadata unknown
      scaleUnit - unit of bin extent by which bin values are divided for density-like combiners; may be null for unknown/natural units
      Returns:
      metadata for combined values; the content class must be be a primitive numeric wrapper class

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getKnownCombiners

      public static Combiner[] getKnownCombiners()
      Returns a list of the known general purpose instances of this class.
      Returns:
      combiner list

    • createQuantileCombiner

      public static Combiner createQuantileCombiner(String name, String descrip, double quantile)
      Creates a combiner that calculates a given quantile.
      Parameters:
      name - combiner name
      descrip - minimal description, or null
      quantile - quantile point, between 0 and 1
      Returns:
      combiner

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