Package uk.ac.starlink.table.join
Class ErrorCartesianMatchEngine
java.lang.Object
uk.ac.starlink.table.join.AbstractCartesianMatchEngine
uk.ac.starlink.table.join.ErrorCartesianMatchEngine
- All Implemented Interfaces:
MatchEngine
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
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Constructor Summary
ConstructorsConstructorDescriptionErrorCartesianMatchEngine
(int ndim, ErrorSummation errorSummation, double scale) Constructor. -
Method Summary
Modifier and TypeMethodDescriptionReturns a supplier for coverage objects.Returns a factory for MatchKit instances corresponding to the current settings of this object.uk.ac.starlink.table.DescribedValue[]
Returns a set of DescribedValue objects whose values can be modified to modify the matching criteria.uk.ac.starlink.table.ValueInfo
Returns a description of the value returned by theMatchKit.matchScore(java.lang.Object[], java.lang.Object[])
method.double
getScale()
Returns the distance scale.double
Returns unity.uk.ac.starlink.table.ValueInfo[]
Returns a set of ValueInfo objects indicating what is required for the elements of each tuple.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.toString()
Methods inherited from class uk.ac.starlink.table.join.AbstractCartesianMatchEngine
getBinFactor, getIsotropicScale, getNdim, getScale, getTuningParameters, setBinFactor, setIsotropicScale, setScale
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Constructor Details
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ErrorCartesianMatchEngine
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
- dimensionalityerrorSummation
- how to combine errors; if null, simple is usedscale
- rough scale of errors
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Method Details
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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
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getScale
public double getScale()Returns the distance scale.- Returns:
- characteristic scale of errors
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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'snullable
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
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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 callingDescribedValue.setValue(java.lang.Object)
on the returned objects.- Returns:
- array of described values which influence the match
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getMatchScoreInfo
public uk.ac.starlink.table.ValueInfo getMatchScoreInfo()Description copied from interface:MatchEngine
Returns a description of the value returned by theMatchKit.matchScore(java.lang.Object[], java.lang.Object[])
method. The content class should be numeric (though need not beDouble
), and the name, description and units should be descriptive of whatever the physical significance of the value is. If the result ofmatchScore
is not interesting (for instance, if it's always either 0 or -1),null
may be returned.- Returns:
- metadata for the match score results
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toString
- Specified by:
toString
in classAbstractCartesianMatchEngine
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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
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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 itsCoverage.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
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getScoreScale
public double getScoreScale()Returns unity.- Returns:
- scale of successful match scores, a positive finite number or NaN
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