Package uk.ac.starlink.table.join
Class FixedSkyMatchEngine
java.lang.Object
uk.ac.starlink.table.join.AbstractSkyMatchEngine
uk.ac.starlink.table.join.FixedSkyMatchEngine
- All Implemented Interfaces:
MatchEngine
- Direct Known Subclasses:
FixedSkyMatchEngine.InDegrees
MatchEngine which matches objects on the celestial sphere with a
fixed maximum separation.
The tuples it uses are two-element arrays of
Number
objects, representing Right Ascension and Declination respectively
in radians. Other similar longitude/latitude-like coordinate systems
may alternatively be used.- Since:
- 6 Sep 2011
- Author:
- Mark Taylor
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
MatchEngine class that behaves like FixedSkyMatchEngine but uses human-friendly units (degrees and arcseconds) rather than radians for tuple elements and match parameters. -
Constructor Summary
ConstructorsConstructorDescriptionFixedSkyMatchEngine
(SkyPixellator pixellator, double separation) 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
Returns a scale value for the match score.double
Returns the maximum separation which corresponds to a match.uk.ac.starlink.table.ValueInfo[]
Returns a set of ValueInfo objects indicating what is required for the elements of each tuple.void
setSeparation
(double separation) Sets the maximum separation which corresponds to a match.toString()
Methods inherited from class uk.ac.starlink.table.join.AbstractSkyMatchEngine
calculateSeparation, getPixellator, getScale, getTuningParameters, isSkyPosition, setScale
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Constructor Details
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FixedSkyMatchEngine
Constructor.- Parameters:
pixellator
- handles sky pixellisationseparation
- initial value for maximum match separation, in radians
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Method Details
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setSeparation
public void setSeparation(double separation) Sets the maximum separation which corresponds to a match.- Parameters:
separation
- maximum separation in radians
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getSeparation
public double getSeparation()Returns the maximum separation which corresponds to a match.- Returns:
- maximum separation in radians
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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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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()Description copied from interface:MatchEngine
Returns a scale value for the match score. The intention is that the result ofmatchScore
/MatchEngine.getScoreScale()
is of order unity, and is thus comparable between different match engines.As a general rule, the result should be the maximum value ever returned from the
matchScore
method, corresponding to the least good successful match. For binary MatchEngine implementations (all matches are either score=0 or failures) a value of 1 is recommended. If nothing reliable can be said about the scale, NaN may be returned.- Returns:
- scale of successful match scores, a positive finite number or NaN
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toString
- Specified by:
toString
in classAbstractSkyMatchEngine
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