Class ErrorCartesianMatchEngine

java.lang.Object
uk.ac.starlink.table.join.AbstractCartesianMatchEngine
uk.ac.starlink.table.join.ErrorCartesianMatchEngine
All Implemented Interfaces:
MatchEngine

public class ErrorCartesianMatchEngine extends AbstractCartesianMatchEngine
Match Engine which works in an N-dimensional Cartesian space with isotropic per-row errors. Tuples are N+1 element, with the last element being the error radius, so that a match results when the distance between two objects is no greater than the combination of their error radii. This combination may be either a simple sum or the sum in quadrature, according to configuration.
Since:
1 Sep 2011
Author:
Mark Taylor
  • Constructor Details

    • ErrorCartesianMatchEngine

      public ErrorCartesianMatchEngine(int ndim, ErrorSummation errorSummation, double scale)
      Constructor.

      The errorSummation parameter configures how the match score is assessed from the error values of two tuples. The match threshold is determined by summing the error values, either by simple addition or by addition in quadrature.

      Parameters:
      ndim - dimensionality
      errorSummation - how to combine errors; if null, simple is used
      scale - rough scale of errors
  • Method Details

    • setScale

      public void setScale(double scale)
      Sets the distance scale, which should be roughly the average of per-object error distance This is just used in conjunction with the bin factor for tuning.
      Parameters:
      scale - characteristic scale of errors
    • getScale

      public double getScale()
      Returns the distance scale.
      Returns:
      characteristic scale of errors
    • getTupleInfos

      public uk.ac.starlink.table.ValueInfo[] getTupleInfos()
      Description copied from interface: MatchEngine
      Returns a set of ValueInfo objects indicating what is required for the elements of each tuple. The length of this array is the number of elements in the tuple. Each element should at least have a defined name and content class. The info's nullable attribute has a special meaning: if true it means that it makes sense for this element of the tuple to be always blank (for instance assigned to no column).
      Returns:
      array of objects describing the requirements on each element of the tuples used for matching
    • getMatchParameters

      public uk.ac.starlink.table.DescribedValue[] getMatchParameters()
      Description copied from interface: MatchEngine
      Returns a set of DescribedValue objects whose values can be modified to modify the matching criteria. Typically at least one of these will be some sort of tolerance separation which determines how close tuples must be to count as a match. This match engine's behaviour can be modified by calling DescribedValue.setValue(java.lang.Object) on the returned objects.
      Returns:
      array of described values which influence the match
    • getMatchScoreInfo

      public uk.ac.starlink.table.ValueInfo getMatchScoreInfo()
      Description copied from interface: MatchEngine
      Returns a description of the value returned by the MatchKit.matchScore(java.lang.Object[], java.lang.Object[]) method. The content class should be numeric (though need not be Double), and the name, description and units should be descriptive of whatever the physical significance of the value is. If the result of matchScore is not interesting (for instance, if it's always either 0 or -1), null may be returned.
      Returns:
      metadata for the match score results
    • toString

      public String toString()
      Specified by:
      toString in class AbstractCartesianMatchEngine
    • createMatchKitFactory

      public Supplier<MatchKit> createMatchKitFactory()
      Description copied from interface: MatchEngine
      Returns a factory for MatchKit instances corresponding to the current settings of this object.

      The returned value is immutable, and is not affected by subsequent changes of the settings of this object.

      Returns:
      match kit supplier
    • createCoverageFactory

      public Supplier<Coverage> createCoverageFactory()
      Description copied from interface: MatchEngine
      Returns a supplier for coverage objects. Each such coverage can be used to characterise a region of tuple space. When populated with a set of tuples A, any tuple for which the inclusion function defined by its Coverage.createTestFactory() method returns false is guaranteed not to match any tuple in A according to this object's match criteria.

      The returned value is immutable, and is not affected by subsequent changes of the settings of this object.

      If no suitable implementation is available, null may be returned.

      Returns:
      supplier of coverage objects, or null
    • getScoreScale

      public double getScoreScale()
      Returns unity.
      Returns:
      scale of successful match scores, a positive finite number or NaN